i Publication of The College of ' Y OF CALIFORNIA in^ f y Js?m, PROTECTING CITRUS GROVES FROM FROST COSTS AND BENEFITS TO GROWERS R. L. ADAMS r. -;-* ; " die'/ <$*?. *:. *..-.>- \,>, lil^ g*sf ft v^>-^ ^ CALIFORNIA AGRICULTURAL Experiment Station m Service BULLETIN 730 •^ifei! , •- ^^ n - ■ he winter of 1949-50 — the third freezing winter in as many years — brought the southern California citrus industry to a crisis. Damage was widespread, despite large outlays for orchard heating. Smoke conditions were unusually bad and caused vigorous protest from urban areas. In response to this critical situation, the Giannini Foundation of Agricultural Economics undertook to investigate the economic prob- lems of orchard heating, in the concentrated citrus areas of four of southern California's important citrus counties. This bulletin presents the results of this new study. Purposes of this bulletin are two: l.To give latest information on the most effective — and cleanest — systems of protecting citrus groves from frost under the varying con- ditions of southern California. 2. To show under what conditions growers can get their money's worth in frost protection, and under what conditions they cannot. THE AUTHOR: R. L. Adams is Professor of Farm Management, and Agricultural Economist, Giannini Foundation and Experiment Station, Berkeley. TABLE OF CONTENTS BACKGROUND . . . some facts about the California citrus industry and the frost protection problem page 5 The smog question, 5 How important are lemons and oranges? 7 FROST PROTECTION METHODS . . . heating and wind equipment described . . page 8 Heaters, 8 Wind machines — the new trend, 12 WHEN TO PROTECT . . . critical temperatures and what to do about them .... page 1 5 Protection depends on the grower's policy, 1 5 Critical temperatures, 15 Hours of heater and wind machine operations, 16 When to fire heaters, 17 When to start wind machines, 19 When to fire heaters with wind machines, 20 COVERAGE . . . how much to expect your equipment to protect page 24 Coverage: heaters only, 24 Coverage: wind machines only, 25 Coverage: heaters with wind machines, 26 COSTS . . . breakdown of expense items in orchard heating page 29 Installation costs, 29 Overhead costs: heaters, 30 Operation costs: heaters, 33 Fuel storage costs, 36 Overhead costs: wind machines, 39 Operating costs: wind machines, 44 DISCUSSION page 44 Choosing a wind machine, 44 Wind machines — with or without heaters? 47 Comparative costs of frost protection methods, 48 Money available for frost protection, 54 Your grove is an individual problem, 54 Frost protection: the long view, 55 ACKNOWLEDGMENTS page 55 APPENDIX I: A working formula for your investment in frost protection page 56 APPENDIX II: County and city ordinances governing use of heaters page 61 PROTECTING CITRUS GROVES FROM FROST COSTS and BENEFITS R. L. ADAMS BACKGROUND . . . California lemon and orange production runs to millions of dollars annually and cannot be replaced, but smog is a growing problem. Here are some facts to show the need for improved frost protection methods — and better community un- derstanding. THE SMOG QUESTION A three-year repetition of serious frosts never before encountered in the Califor- nia citrus industry— 1947-48, 1948-49, 1949-50 — resulted in the burning of literally millions of gallons of oil. This burning — designed to prevent frost dam- age to fruits and trees — was conducted in various designs, makes, and sizes of metal containers. These pots function with various degrees of combustion ef- ficiency, but there were enough old-style pots of low combustion to generate a pall of smoke, blanketing the heated areas with some damage to the paint on houses, clothing, and goods in stores and ware- houses, to say nothing of the slowing of traffic and reduction in tourist business. In view of the frequency and intensity of firing, especially in the 1948-49 and 1949-50 cold weather periods, towns- people, especially, rose and demanded relief-giving ordinances of various county boards of supervisors and city councils. Ordinances have now been passed by a number of counties and municipalities, and plans are in the making for similar ordinances in other areas. The gist of these ordinances is to out- law certain types of heating equipment that cause objectionable soot and smoke (see Appendix II, page 60). Fortunately there are today new and improved heater designs and additions to some of the older heaters that provide adequate heat unac- companied by excessive soot and smoke. Unfortunately, equipment of groves with new heaters runs into considerable money. (As of July 11, 1950, the price was $5.40. Figuring an average of 45 heaters to the acre of trees, the required investment amounts to $245 per acre.) Coupled with the added cost is a fear expressed by many orange and lemon growers that they will have no assurance of peaceably utilizing this new equipment long enough to justify their investment. They point out, and reasonably, that no present board of supervisors or city coun- cil can control what new boards and councils may do, or give assurance that present boards or councils may not revise whatever is done this year. Both sides have grounds for complaint. Naturally growers fear the consequences of legislation that could so limit their or- chard heating operations as to jeopardize the future of their industry. Inability to heat would result in loss not only of fruit but of trees if and when damaging low [5] temperatures again prevail. This would be particularly true of lemons, which re- quire more frequent heating than or- anges, and lighting of heaters at higher temperatures. People not directly connected with citrus grove requirements and practices do not always look beyond the damage and discomforts that prolonged heating imposes under present-day conditions. To appreciate what the citrus industry means to each of the southern California counties where citrus production is wide- spread, let us look at the figures. Table 1. Value of Lemons and Oranges in Seven Southern Counties: 1948, 1949 and 1950 County Fruit Value Three-year average of totals 1948 1949 1950 Santa Barbara . . Lemons $ 6,828,426 $ 7,846,414 $ 7,135,953 Oranges Totals 66,097 47,577 43,910 6,874,523 7,893,991 7,179,863 $ 7,316,126 Ventura Lemons 18,408,680 25,336,388 18,678,086 Oranges Totals 15,519,570 13,046,498 14,352,330 33,928,250 38,382,886 33,030,416 35,113,851 Los Angeles ... Lemons 8,532,500 8,287,700 9,823,000 Oranges Totals 18,345,700 16,086,600 21,372,500 26,878,200 24,374,300 31,195,500 27,482,667 Orange Lemons 3,866,830 4,373,000 3,480,000 Oranges Totals 29,014,080 32,376,000 28,480,000 32,880,910 37,749,000 31,960,000 34,199,970 Riverside Lemons 2,513,230 4,204,590 2,481,730 Oranges Totals 11,101,500 9,831,910 11,159,230 13,614,730 14,036,500 13,640,960 14,194,473 San Bernardino Lemons 3,974,430 3,412,749 3,554,073 Oranges Totals 18,320,855 8,113,542 9,317,189 22,295,285 11,526,291 12,871,262 15,564,279 San Diego Lemons 3,600,758 4,259,762 3,119,565 Total: Seven counties .... Oranges Totals 2,702,754 3,262,090 2,723,165 $ 6,303,512 $ 7,521,852 $ 5,842,730 6,556,031 $138,427,397 [6] HOW IMPORTANT ARE LEMONS AND ORANGES? Production of lemons and oranges in southern California annually reaches well up in the millions of dollars. Any step taken to curtail production reduces these values. Their importance is best illus- trated by presenting the value of lemons and oranges, both navels and Valencias, for 1948, 1949, and 1950 (table 1). Grapefruit are excluded since the output is relatively small. Byproducts are in- cluded if the data assign them to lemons or oranges; otherwise, if unsegregated, the figures are not shown in the table. Data have been assembled for the south- ern California counties of Santa Barbara, Ventura, Los Angeles, Orange, Riverside, San Bernardino, and San Diego. Lemons and oranges vs. other agricultural commodities. The rela- tive importance of lemons and oranges in comparison with other agricultural products is enlightening. To illustrate the position of these citrus fruits in relation to deciduous tree fruits, including wal- nuts; grapes, truck crops, field crops, in- cluding seed production ; and subtropical fruits — avocados, olives, dates, persim- mons, etc., data were totaled for the past three years from the following counties: Santa Barbara, Ventura, Los Angeles, Orange, Riverside, San Bernardino, and San Diego. The data show: Value of all products shown . $313,204,660 Value of citrus fruits 150,593,654 Percentage value of citrus fruits to value of all prod- ucts shown 48.1 Attention may well be directed to what the citrus industry amounts to in the hir- ing of labor, purchase of spray materials, fertilizers, payments for irrigation water (from water districts) , use of motors, etc. Add to the payments by growers, expend- itures for and by packing houses — labor, crates, wrapping paper, and the like. Then add (1) the by-products fac- tor, the business given to the railroads, truckers, commission merchants, etc., and (2) purchases by growers for their fam- ily and personal accounts, and the total is staggering. In analyzing these figures one should bear in mind that if a substantial block of citrus had to be removed because of lack of adequate protection in frost years, there is no crop or agricultural enterprise available for large-scale substitution that could in any way fill the void created by the uprooting of citrus trees on a whole- sale scale. Citrus trees are a "natural" on many of southern California's rather open soil types often located on rolling terrain, and on land held at substantial values ($1,000 and $2,000 an acre, for example), where water costs are often relatively high and where there are many small-sized farm units. There could be some, though limited, expansion of vegetable growing, poultry, rabbits, vineyards, and certain deciduous trees, but any of these, as a replacement for good groves, would be a penny wise, pound foolish change of pattern. Any extensive inclusion of beef cattle production, dairying and other livestock enterprises — occasionally men- tioned locally as possibilities — are not promising. [7] FROST PROTECTION METHODS . . . involve heaters and wind machines of various types. Here is a description of how they work, and how widely they have been used. HEATERS Heating equipment designed and in- stalled to reduce frost damage to citrus fruits and trees is not new to California. As far back as the freeze of 1912-13, artificial heat was used to raise danger- ously low temperatures. That winter, small open heaters were credited with saving lemons on a large lemon grove in southern California where frost dam- age to both fruit and trees generally was widespread. Early demonstrations of the economic feasibility of orchard heating were re- sponsible for the sale of more than 900,000 heaters to California citrus grow- ers during 1922-25. In 1930, 67,791 acres were reported as heated in the districts of Lindsay, Santa Paula, Azusa, Pomona, Upland, Red- lands, Corona, and Whittier. In 1938, the acreage had increased to 90,695. Stated in percentage of heated to total acreage, the figures are 30.3 per cent for 1930 and 20.2 per cent for 1938. An idea of the types and relative num- bers of heaters recently in operation is given in the accompanying summaries of three counties (tables 2, 3, 4) . Types of heaters. Over the years manufacturers have developed various types and styles of heaters for use in rais- ing critical temperatures. Most of these are designed for burning oil although there are a few types built to use butane, coke, and briquets. Bowl or distilling heaters, by far the most common kind, burn a gas oil fuel known as bunker grade Marine Diesel with a minimum of 27° A.P.I. (American Petroleum Institute) gravity and selected for low pour point. Bunker grade fuel is selected because it has a pour point of 0° F or lower, a low carbon residue, and a high degree of A.P.I, gravity. The rules and regulations of the Air Pollution Control District of Orange County, approved September 6, 1950, state that, if available, distillate fuel used in heaters (pipeline and return stack ex- cepted) must contain no cracked material and must have a minimum of 31° A.P.I, gravity at 60° F. Other minimum speci- fications cover flash point, distillation, carbon residue, and sulfur content. A recent change in the kind of oil used in the bowl or distilling heater is illus- trated by the purchases made for the Crafton-Mentone Protective Association. Before the smudge issue became impor- tant, oil with a 26-28° A.P.I, gravity and a pour point of 15° F or less was bought from the refinery for use by stockholders of the association owning citrus groves. Now, however, oil being purchased and burned has a 32-34° A.P.I, gravity and is a #1 diesel. Basically, the bowl or distilling heater consists of an oil reservoir (a round or square bowl) with a cover and a com- bustion chamber or lazy flame stack cen- trally located upon the cover. Each heater is equipped with an air intake regulator, gases being generated in the reservoir for burning in the stack above. Generator or pipeline heaters usu- ally require a fuel marketed as kerosene, distillate, or stove oil, which is a com- paratively high grade orchard heating fuel. Samples of this grade, tested from the regular stock of three California re- fineries in 1937, showed a range of 37° to 38.3° A.P.I, gravity. The oil pipeline heater is equipped with a generator to volatilize the fuel fed under pressure from central storage tanks [81 through a pipeline distributing system to the individual heaters. Butane heaters use a butane-propane gas which is piped to individual heaters under pressure. However, the extent of the use of this kind of fuel for heating orchards is very limited and at present is not an important consideration. Butane heaters are similar to the oil pipeline type except that fuel used is a butane-propane mixture instead of oil. Butane must be stored under pressure during the entire season. Coke and briquets are the usual solid fuels burned and special types of heaters have been designed to facilitate Table 2. Census of Types of Heaters, Riverside County, 1950. (Source: Agricultural Extension Service Survey.) Type of heater Number Per cent of total 4,664 1.67 732 .26 7,383 2.65 8,447 3.02 129,773 46.60 36,857 13.20 1,465 .53 1,670 .59 Group A* Return stack Lenora Jumbo cone Exchange 7-inch. . Lazy flame 24-inch Lazy flame 18-inch Pipeline Other Subtotal Group Bf Citrus 15 inch .... Citrus Regular 148 Hy-Lo Special . Other Subtotal Group C{ Dunn Other Subtotal Other § Coke Miscellaneous Subtotal TOTAL 190,991 81,660 1,600 3,250 4,850 400 650 1,050 278,551 68.52 9,951 3.58 40,782 14.65 11,445 4.10 19,482 6.84 29.17 .57 1.17 1.74 .14 .23 .37 100.00 * Approved types under the Riverside County smudge ordinance 367. t Conditionally approved types under ordinance No. 367; elimination or replacement of 1/3 of these each year is required. t Prohibited heaters; unlawful to use, burn or operate under ordinacne No. 367. § These include heaters which are undesignated and which will be granted permits under ordinance No. 367 only if the applicant offers satisfactory proof that they can meet smoke output requirements. [9] their use. Approximately 10 pounds of this type of fuel equals the heat value of a gallon of oil (140,000 B.t.u.). Coke heaters are very simple in con- struction since all that is required is a hollow, metallic bowl about 18 to 24 inches high with a grate near the base and a cover. Air ventilation is usually Table 3. Census of Types of Heaters, Los Angeles County, 1951 (Source: County of Los Angeles Air Pollution Control District.) Type of heater Approved types* Oil pipeline Coke Return stack Butane Kittle Exchange, 7-inch . . Hy-Lo 230 Lazy Flame 24-inch Lazy Flame 18-inch National Junior. . . . Hy-Lo 148 Special . Hy-Lol929No.32. Hy-Lo 148 Jumbo Cone Lemora National Double St. Hy-Lo Double St. . Other Number Subtotal. Conditionally approved types | Baby Cone Citrus 15-inch Citrus regular Exchange 6-inch Exchange 5 1/2-inch Hy-Lo Drum No. 62 Hy-Lo Hot Blast Pheysey-B Hinchcliff Subtotal. 52,800 66,587 13,318 11,358 38,648 5,190 100,458 281,498 143,632 25,670 13,167 4,818 17,496 31,336 11,545 34,995 3,121 1,572 847,209 6,981 3,697 15,015 3,948 9,558 1,310 2,795 121 2,942 TOTAL 46,367 893,576 Per cent of total 5.91 7.45 1.49 .15 4.33 .58 11.25 31.45 16.10 2.88 1.47 .54 1.96 3.51 1.29 3.92 .35 .18 94.81 .78 .41 1.68 .44 1.07 .15 .32 .01 .33 5.19 100.00 ni*tri J^S nno if «- e « hea ^ rs which meet requirements of the Los Angeles County Air Pollution Control Sk£1T,? two ways: 1) meet the one-gram smoke limit at all adjustment settings; (2) at certain adjustments but not with maximum draft, requiring operational adjustment or mechanical alteration fo con ^^^^i^^^^J^/^ :^ S!?rw we , re ,rT de . d: ° P * tion No ' * requires the replaceme* eting the one-gram limit at all adjustment settings, and option No. 2 requ with heaters meeting the one-gram limit with operational adjustment of me- the replacement of 50 per cent with heaters meetinir th« onn-immi limit ™*v, 7!Ll*£L-T -!J".tiZ:_li e jl~ s chanical alternation. [io Table 4. Census of Types of Heaters, Orange County, March 1951. 7,586 Acres Classified. (Source: D. W. Tubbs, Agricultural Commissioner, Orange County.) Type of heater Number Return stack, coke, pipeline, kittle 52,151 24-inch lazy flame, Hy-Lo 230-A, 18-inch lazy flame, 18-inch National Junior Louvre, Lemora, Jumbo Cone, 6-inch Exchange, 7-inch Ex- change, 20-inch Scheu, Double wick kerosene, Special (18-inch Junior Louvre 15-inch citrus), 15-inch Citrus plus stovepipe, 20-inch double sections, and Hy-Lo 148 special 204,880 Citrus stub, Citrus 15-inch, Citrus gas flame, 5 ' L >-inch Exchange, Baby Cone, O'Keefe and Merritt, National Double stack, Hy-Lo 148 Original, Hy-Lo Drum, Hy-Lo Hot Blast, Hy-Lo 1929, Hy-Lo Short stack, 15-inch Junior Louvre, Scheu 24-inch (old style), Scheu 20-inch (old style), and Dunn (modified) 19,169 Total ( 276,200 achieved through an opening on the side of the heater, near the base, or from below the heater through the grate. Types of heaters in extensive use today (omitting heaters outlawed or condition- ally approved by recent county or city ordinance affecting use of heaters) con- sist principally of the 24-inch lazy flame, the 18-inch lazy flame, jumbo or large cone, and the oil pipeline. The university return stack is also discussed because its use will increase in the near future (prob- ably less than 2 per cent of the heaters in use today are of this type) . Lazy flame heaters are constructed simply. Both the 24- and the 18-inch type have a simple, cylindrical galvanized metal stack. The 24- and 18-inch dimen- sions refer to the height of stacks. These heaters are designed to cause most of the combustion to take place at or above the top of the stack. Bowls are constructed of galvanized metal and are either round or square, each having a capacity of nine gallons. The air intake to these heaters is usually accomplished with downdraft tubes extending down into the bowl from the bowl cover or as an internal chimney which extends from the base of the stack down into the bowl. The purpose of an air intake is to distribute primary air, make starting easier and force the burn- ing of the oil clear down to the bottom of the bowl. It is estimated that about 65 per cent of the heaters in use today are of the lazy flame type, about 50 per cent being 24-inch stack, and 15 per cent being 18-inch stack. Regulators for these heaters are devices on the bowl covers to control the air draft. The Jumbo or Large Cone heater is a combustion chamber type and differs from the lazy flame type only in the stack. The width of the stack increases greatly near its base, then tapers throughout its entire height, the tapering being pro- nounced at just above the base, the chim- ney then graduating to a less pronounced taper. Combustion takes place mainly in the enlarged chimney chamber near and just above the base of the stack. This dif- fers from the lazy flame heaters in that most of the combustion here occurs above [in the stack. Holes or louvers are present only in the combustion chamber area of the stack. This heater is somewhat larger than the 24-inch lazy flame, both in height of heater and the diameter of the stack. Probably about 3 per cent of the heaters in use today are of this type. However, their importance may increase because of recent findings by the University of California, Division of Agricultural En- gineering at Davis. Results similar to those achieved with the University return stack may be accomplished by adding a return pipe to the Jumbo Cone heaters. Heaters with stacks less than four feet in height are designated as short stack heaters ; those of four feet or more as tall stack heaters. Return stack heaters, with special reference to the University Return Gas Stack Heater developed by A. S. Leonard of the University of California, Division of Agricultural Engineering at Davis, is unique in several ways. This heater is equipped with a lower and upper stack, combustion taking place mostly in the louvered lower stack. The lower stack, or combustion chamber, tapers from a 6-inch diameter at the top of the bowl cover to 8% inches at the point where it fits into the upper stack. The upper stack (S^-inch diameter, cylindrically shaped and unlouvered) has an opening through which a 3-inch return pipe is fitted. The purpose of this pipe is to carry some of the combustion products back into the bowl in order to dilute the fuel vapors. Cast-iron elbows are now used both in- side and outside the stack opening to insure longer life of these parts. Fitting the return pipe into the bowl requires an opening so that growers who wish to con- vert their heaters to the return stack type must have their old bowl covers altered to that extent. Regulators on the return stack heaters are completely closed as soon as possible after lighting to insure normal operation. This heater is relatively smokeless if it is operated properly. Oil pipeline or generator heaters are those which have fuel fed to them through a pipe line permanently placed in the grove and so located that burners are permanently located at allotted spots. The heater itself consists mainly of a burner or generator, which contains ele- ments for evaporating oil with the heat of the heater flame and issuing it from an orifice as a vapor jet where it burns in a self-induced draft. Other parts of the heater include needle valves for regulat- ing the burning rates, a metal bowl, and a cover for supporting the burner and directing the flame. About 4 per cent of the heaters used in California today ap- pear to be of this type. Fuel consumption of various types of heaters is given in table 5. WIND MACHINES— THE NEW TREND Up to about 1945, reliance of citrus growers against frost was confined al- most entirely to oil burning heaters or pots, with some use of coke and briquets, and butane. According to one report, wind ma- chines were used in Tulare County 30 years ago, although most of the early ma- chines were abandoned after a short period of use. Many new installations were made there, however, in the 1930s and by 1939 there were an estimated 75 wind machines (commonly called blow- ers) in the county; 52 were electrically powered and 23 gasoline driven. Today there are more than 2,700 wind machines in California, as compared to an estimated 133 in 1938. In Orange County there were about 235 machines in 1950 as compared to one or two dozen in 1945. According to an orchard heater survey made by the Agricultural Exten- sion Service in 1950, Riverside County had 2,336 acres equipped with wind machines as compared with 6,516 acres protected with heaters only. But 88 per cent of the acreage under wind machine protection had supplementary heaters. [12] Table 5. Results of Fuel Consumption Tests Made by Don Beard of the Stewart Citrus Association, Upland, California.* Gallons of Type of heater Hours burned Kind of fuel used fuel per heater hour Remarks 18-inch lazy flame 19 1/6 "smudge" oil .468 Very smoky and soots up. (no downdraft) Burns with a reddish dirty flame 18-inch lazy flame 19 1/2 "smudge" oil .462 Burned well. Soot formed (downdraft under stack) 18-inch lazy flame 22 "smudge" oil .409 Quite smoky. Easiest to (downdraft under light. Flame was a little damper) reddish. Return stack 17 1/6 dirty "smudge" oil .530 Very little smoke. Burned clean down to dry ash. Regular even heat until the last hour Lemora 14 "smudge" oil .643 Smokes some, soots up and difficult to clean. Puts out a good heat 24-inch lazy flame . . . 19 1/6 1/2 kerosene, 1/2 "smudge" oil .468 White flame, little smoke, very little soot 24-inch lazy flame . . . 20 1/3 tractor diesel oil .443 Not much smoke, flame was a little red, quite a bit of soot formation 24-inch lazy flame . . . 39 dirty "smudge" oil .462 Burned 22 hours on 9 gal- lons but only 17 after being refilled but not cleaned Return stack. 30 dirty "smudge" oil .600 Burned 16 hours on 9 gal- lons but only 14 hours after being refilled * Mr. Beard says, "The lazy flame type of heater is the life of them all. This longer life is due to the fact that they don and, although they are the easiest heater to clean, they need to easiest one t get hot sta be cleaned to regulate, and has the longest cks. However, they soot up badly too often." Types of wind machines. Wind ma- chines typically consist of a tower, equipped with a single propeller (similar to an airplane) driven by an electric motor, gasoline, or diesel engine. Some machines, called duals, have two engines and two propellers mounted on a single tower. The basic idea of a wind machine is to disturb the air so that the colder currents are mixed with the warmer ones. [13] thus raising temperatures within a grove so equipped. This is accomplished by rotating the propeller at high speeds (900 to 1,300 revolutions per minute). These machines do not and are not expected to warm the air. Their function is to raise temperatures by drawing together and mixing currents of different temperatures. Obviously, to be successful, there must be warm air available for mixing. When no warm air is available overhead (or in the grove), then the wind machines cannot of themselves effect a temperature rise. Data collected from 17 groves indicate the following structural variations in wind machines: Tower heights varied from 30 to 40 feet, with the majority at 30 feet. Propellers varied in diameter from 8 to 13 feet, depending on the horse- power of the motor or engine. Propellers were constructed of metal, wood, or wood with plastic covering. Propeller speed re- portedly varied from 900 to 1,300 revo- lutions per minute. 19 of the 24 machines were constructed to rotate through a 360- degree arc (except one, which was set for a 220-degree arc). Time per rotation varied from 2 to 9 minutes. Rotations were mostly counterclockwise (one out of 19 moved clockwise). Our study of years of installation and types of machines reveals the following trends in wind machine acceptance: 1939—1 electric; 1943—1 gasoline; 1945 — 3 gasoline; 1947 — 3 gasoline; 1948 — 7 electric, 33 gasoline, 2 diesel; 1949 — 19 electric, 9 gasoline, 5 diesel. A 90-95 per cent complete count of wind machines in California (1950) shows that, of 2,779 machines, 1,561 were gasoline machines; 1,018 were electrics; and 200 were diesels. Of the total, 1,625 were located in four counties — Riverside, San Bernardino, Orange, and Los An- geles — with proportions of 914 gasoline, 546 electric, and 165 diesel machines. A random sample of 42 groves with a total of 53 wind machines shows pur- chases as given in table 6. Popularity of the wind machine. The evidence indicates that growers to- day are convinced that the wind machine can play an important part in programs of frost control. During the past year, the number of wind machine installations has apparently equaled the number in- stalled during the preceding three years. The major question in the minds of most growers seems to center in the cost of installation and operation rather than in the efficiency of the equipment. The increasing popularity of the wind machine for citrus is based upon four facts. 1 . The machine itself has been im- proved in efficiency, reliability, and economy. 2. The cost of oil and labor has gone up increasingly, thus reacting unfavor- ably on use of heaters. Oil is a major item in the cost of frost protection, especially during the coldest years. A representative of the Crafton-Mentone Protective Association of Redlands sup- plies this data on the average refinery cost of oil to his organization: 1938 — $.0375; 1939— 1.03-.035; 1940— $.03- .035; 1941— $.03-.035; 1942— $.035; 1943— $.035; 1944— $.04; 1945— $.0425; 1946— $.05; 1947— $.06; 1948 —$.07; 1949— $.09; 1950 (to November 13)— $.07. -3. Two winters of serious freezing weather for citrus (1948-49 and 1949- 50), together with an increase in urban population, have produced legislation and sentiment against the use of smoke- producing heaters for frost protection. 4. Recent successes in frost protection, using a limited number of heaters in con- junction with wind machines on high ceiling nights, have given growers more confidence in machines. Many skeptics are still asking if a wind machine raises temperatures on nights when there is no warm air overhead. The answer lies in providing a moderate number of heaters for use as a supplement to the wind ma- chines. [14] Table 6. Sampl e Wind Machine Installations. Number of groves Acreage Number of wind machines Type of wind machine 7 3 5 1 1 10 2 10 4 79 25 50 10 33 111 19 332 67 10 3 5 1 1 11 2 16 5 12 1/2 h.p. electric motored 25 h.p. electric motored 50" h.p. electric motored 60 h.p. electric motored 100 h.p. electric motored 100 h.p. single propeller ; gasoline motored 145 h.p. single propeller ; gasoline motored 100 h.p. dual propeller ; gasoline motored 110 h.p. dual propeller ; gasoline motored WHEN TO PROTECT . . . depends on the system used, the grower's policy, and the variety and age of trees and fruit. This section presents records of critical temperatures in your area — and recommendations on when to use your equipment. PROTECTION DEPENDS ON THE GROWER'S POLICY Ideas differ somewhat among growers as to when the wind machines should be turned on or the heaters lighted. One fac- tor is how much protection a grower thinks justified. If his program calls for saving only the trees, letting the crop freeze, he will postpone his use of frost- protective measures until temperatures are much lower than if he plans to save the fruit. And here, again, the size of the fruit to be saved is a factor. If the aim is to save blossoms, the small "button" lemons, or the small immature oranges, then heating or wind machine operations must be started when the temperatures are relatively high, compared with start- ing operations for the mature or maturing crop, and higher for the crop than when tree protection is the sole aim. CRITICAL TEMPERATURES In order to show the time of occur- rence, extent, and frequency of critical temperatures liable to injure citrus trees and fruit on the trees, data from the files of the United States Weather Bureau lo- cated in the Post Office Building at Po- mona are presented in tables 7, 8, and 9.* The selected temperatures follow a study made some years back when the critical temperatures were thought to be 30° for lemons; 27° for green, immature oranges; 26° for ripe oranges. These tem- peratures are sufficiently high to protect the trees. Protection of trees, we may note in passing, depends on the succulence of the growth, protection starting at a some- what higher level when the trees are sappy than when the trees have entered into a degree of dormancy. Frosts occurring unseasonably early (such as a cold spell following warm weather) , presence of ample soil moisture, or unexpended fer- * The author and his associates in the present study herewith express their appreciation and thanks to Messrs. Floyd Young and Roy Rogers for their helpfulness in making available and explaining the various records. (See Acknowl- edgments, page 55.) [15 tilizers or other factors that promote con- tinuation of growth make the fruit and trees more than normally susceptible to frost damage. The tables show low temperature data collected over the years since 1934-35 for the Claremont area in east Los An- geles and west San Bernardino counties; Orange County; and the Redlands area in San Bernardino County. Over the years, data have been accumulated from 9 selected stations in the Claremont area (9 stations since 1938-39) ; 7 selected stations in the Orange County area (8 stations since 1938-39) ; and 3 selected stations continuous since 1934^35, 2 ad- ditional for the years 1934-35 to 1942- 43, inclusive, but with breaks in data, 1943-44 to 1949-50, inclusive. The data year is for each winter, frosts seldom occurring before November or after Feb- ruary. Three levels of low temperatures were compiled from the available data, namely, 30° and lower to 27°, 27° and lower to 26°, and 26° and lower. The tables bring to light some interesting facts. HOURS OF HEATER AND WIND MACHINE OPERATIONS Table 10 shows the wide range of heater usage in different years and in different localities. The table shows (1) the great- est amount of firing, (2) the least amount of firing, and (3) the frequency of hours of firing. Table 11 shows the similarly wide range of wind machine operation during the same years. The table shows (1) the longest recorded use, (2) the least re- Table 7. Critical Temperature Data: Claremont Area. Average hours of low temperatures* Temperatures degrees F Stations No. 13 No. 17 No. 18 No. 31 No. 40 No. 48 No. 49 No. 50 No. 67* All stations 30 to 27 27 to 26 26 and lower . . 54 9 20 16 1 5 23 3 3 40 8 5 53 10 6 16 2 2 29 6 10 61 10 8 59 11 14 36 6 7 * Averages are for the seasons 1934-35 through 1949-50 except station No. 67, its average being for the seasons 1939-40 through 1949-50; all stations' averages exclude data for station No. 67. Location and Elevation of Temperature Stations Station no. Location Elevation (feet) 13 Northeast corner of Euclid Avenue and 19th St., Upland 1,600 17 South side of 25th St. (San Antonio Heights), Upland . 2,125 18 Southwest corner of Mountain Ave. and 15th St., Upland 1,485 31 Southwest corner of San Antonio Ave. and 7th St., Upland 1,165 40 Central Avenue, first small grove south of Narod Union Church, Narod section 940 48 West side of Mountain Ave. at 22nd St., Upland 1,875 49 50 North side of Arrow Rd. about 300 feet east of Mills Ave., Claremont. South side of East Holt Ave. about 1/6 mile east of San Antonio wash (between Ontario and Pomona) 1,100 935 67 Southwest corner of San Antonio Ave. and G St., Ontario 1,040 [16] corded use, and (3) the frequency of hours of machine operation. The data hardly need comment. WHEN TO FIRE HEATERS The Cooperative Extension Office of the University of California and the United States Department of Agriculture located in Riverside County offer the fol- lowing statements concerning the fruit temperatures at which freezing begins. Lemons Button lemons (up to %" dia.) 29.5° to 30.5° Tree-ripe lemons. . . 29.5° to 30.5° Green lemons (larger than i/ 2 " dia.) . . . 28.5° to 29.5° Buds and blossoms 27.0° Thermometers under shelter should in- dicate air temperature. Fruit tempera- tures in lemons exposed to the sky will be as low or slightly lower than air tem- peratures. Lemons sheltered by foliage are usually about one degree warmer than those exposed to the sky. To save button lemons light heaters in time to hold sheltered thermometer at about 30°. To save large green lemons (larger than I/2" diameter) keep the sheltered thermometer above 28°. Damp nights are more dangerous than dry nights with similar temperatures. If ice forms on the fruit early in the night, the larger size green lemons may show rind injury (brown spots) even though the temperature does not fall much below Table 8. Critical Temperature Data: Orange Area, Average hours of low temperatures* Temperatures, degrees F Stations No. 16 No. 19 No. 25 No. 26 No. 41 No. 43 No. 55 All stations 30 to 27 26 3 4 44 5 6 47 8 9 33 3 4 60 12 12 47 5 2 34 4 4 43 27 to 26 6 26 and lower 6 * Averages are for the seasons 1934-35 through 1949-50 except station No. 55, its average being for the seasons 1939-40 through 1949-50; all stations' averages exclude data for station No. 55. Location of Temperature Stations Station No. Location 16 19 25 26 41 43 55 West side of Placentia Ave., about one-half mile north of East Chapman Ave., Placentia. North side of East Chapman Ave., about one-half mile east of the Fullerton Union High School, Fullerton. South Side of West Collins St. and about one-fourth mile west of Batavia Ave., Orange. East side of the Orange-Olive highway, about one and one-half miles south of the town of Olive. North side of First St., about one-half mile east of highway 101, Tustin. West side of Richfield Road, about one-eighth mile south of Torba Linda Blvd., Yorba Linda. West side of Richfield Road, about one-eighth mile north of Placentia Ave., Anaheim. 17 31°. Such damage is of very infrequent occurrence in most districts. It has been caused also by wet snow remaining on the fruit throughout the night. Lemons of all sizes are likely to cool considerably below their freezing points on dry nights before freezing begins, and if the duration of the low temperature is not too great they may warm up again in the morning without injury. Oranges Green oranges 28.5° to 29.5° Half-ripe oranges . . .28.0° to 29.0° Ripe oranges 27.0° to 28.0° Sheltered thermometer indicates air temperature. Fruit temperatures are prac- tically always higher than air tempera- tures when the temperature is falling, but with a stationary temperature for an hour or more the fruit may be as cold, or even slightly colder, than the air. When the air temperature falls rapidly the fruit may be as much as 7° wanner than the air. On cold nights folio win- warm days (highest temperature 60 or over) with steady temperature fall to the danger point: Fire ripe oranges at 2(> . (Sheltered thermometer. I Fire green or half-ripe oranges al 27 . On cold nights following cool days (highest temperature 59° or lower) with very slow temperature fall near danger point: Fire ripe oranges at 27°. (Sheltered thermometer.) Fire green or half-ripe oranges at 27.5°. (These recommendations based on completing first lighting of heater- within 30 minutes.) Keep your shelter thermometer up to 28° or higher on both types of nights after firing is begun. Table 9. Critical Temperature Data: Redlands Area. Average hours of low temperatures* Temperatures, degrees F Stations No. 7 No. 8 No. 36 No. 42* No. 45* All stations* 30 to 27 31 5 10 44 9 8 100 16 7 39 75 58 27 to 26 5 3 17 18 10 26 and lower 8 * Averages are for the seasons 1934-35 through 1949-50 except station No. 42, its average being for the seasons 1934-35 through 1947-48, and station No. 45, its average pertaining to the seasons 1934-35 through 1942-43 and 1947-48 through 1949-50; all stations' averages exclude data for stations No. 42 and No. 45. Location and Elevation of Temperature Stations Station no. 36 42 45 Location Southwest corner of Clifton Ave. and private road, Redlands North of East Lugonia Ave., one-fourth mile east of Judson St., Red- lands Northeast corner of San Bernardino Ave. and Nevada St., Redlands Northwest corner of Texas and San Bernardino Ave., Redlands Northwest corner of Citrus Ave. and the Santa Fe R.R. right of way, Redlands Elevation feet 1,450 1,525 1,210 1,300 1,200 [18] Table 10. Hours of Use of Heaters. 1949-50 1948-49 1947-48 Hours of firing : Highest 186 10 210 24 140 Lowest 4 Number of groves Less than 30 7 8 15 8 9 1 2 12 7 8 9 6 3 12 30 to 60 8 60 to 90 6 90 to 120 4 120 to 150 1 150 to 180 180 to 210 Total 48 47 31 Here again damp nights are more dan- gerous to oranges than dry nights, with similar temperatures. Citrus fruits begin to freeze at a higher temperature when they are covered with ice than when they are dry. The temperature fall is usually slow and steady on damp nights. On dry nights look out for sudden and rapid drops in temperature. If the air temperature fluctuates rapidly up and down, due to wind, the average of the high and low points should be taken as the effective temperature. WHEN TO START WIND MACHINES From our study, the range of tempera- tures at which wind machines are started varied from 27° to 32° F for oranges. Only one out of the 26 growers reporting Table 11. Hours of Use of Wind Machines. 1949-50 1948-49 1947-48 Hours of Use Longest use 400 40 485 30 139 75 Shortest use Under 100 Number of groves 3 9 15 7 1 35 2 4 2 2 1 1 1 100 to 200 200 to 300 300 to 400 400 to 500 Total 11 2 [W started his machine at 32° while only two reported that they waited until the tem- perature dropped to 27° before starting. The rest of the orchardists used tempera- tures from 28° to 31° as the usual time for turning on their wind machines. Twenty-nine and 30° were the most pop- ular for starting machines on oranges. The complete table for oranges was: 32°-l; 31.5°-0; 31°-2; 30.5°-3; 30°- 6; 29.5°-2; 29°-5; 28.5°-2; 28°-3; 27.5°-0; 27°-2. Only seven growers gave data on time of starting wind machines for lemons. One grower starts at 32° F. and six start at 30°. Note that growers start wind machines and light heaters at varying temperatures depending upon the time of the frost sea- son and night. It is common practice for growers to start their machines at a higher temperature early in the season because fruit and trees are generally less resistant to cold. Also, it is usual for them to turn on their machines at higher temperatures early in the night because the cold wea- ther is apt to last long. The fruit and trees are then less able to withstand tem- peratures which would not be serious if they occurred later in the night. WHEN TO FIRE HEATERS WITH WIND MACHINES Data gathered on this subject indicate that heaters are fired generally at 26-28° F for oranges and at 28-30° F for lemons. Because the wind machine is often able to keep the grove temperatures higher than that outside, critical temperatures may be reached later than if no wind ma- chine is used. Some nights it may be un- necessary to light heaters, reliance being placed entirely upon wind machines. Records show that less hours of heating are necessary on the nights when heaters are used in conjunction with a wind ma- chine than when no machine is used. One grower, who uses no heat with a wind machine, is said to have saved fruit even though it froze so hard that you could not stick a knife in it. He did this by running his wind machine until noon, thereby gradually thawing out his fruit instead of letting the early morning sun thaw it out too suddenly. A Corona grower claims that lemons will not freeze at 27° F as long as the wind machine is running and an Oxnard man thinks lemons can stand 25° or less with a machine but no heaters going. GROWERS 1 EXPERIENCE . . . with frost protection shows the great variety of conditions and needs from grove to grove. Here are a few of the many valuable comments collected by our fieldmen. 1 . A grower south of Rialto, who uses no frost protection on 10 acres of oranges, says that the Rialto area is generally warmer than Redlands, and that there has been no frost damage on his grove for the past twenty years, except for the winters of 1947-48, 1948-49, and 1949- 50. Up until the past two winters, how- ever, heaters were used for frost protec- tion. In the winter of 1947-48, his trees were defoliated and his fruit brought him only $.50 per box even though he heated. No tree damage and losses to small outside fruit were the results of the weather dur- ing the 1948-49 season. Nearly a total loss of fruit and extensive tree damage occurred here in the winter of 1949-50. Eucalyptus windbreaks are helpful in controlling frost damage, according to this grower, who noted that there has been less frost damage near them than else- where. He thinks that the windbreaks may possibly radiate some heat to the orange trees and fruit. [20 2. One grower, who operates 40 acres of Valencia oranges located in the Santa Ana Canyon, Prado Dam area (at the junction of Riverside, San Bernardino, and Orange counties), is equipped with 200 pots of the lazy flame type on 15 acres, a 210 h.p. diesel motored wind machine on 15 acres, and the same kind of machine on 10 acres. There are no heaters used in conjunction with the wind machines. The topography rises 80 feet from the river bed to the highest part of the grove, but no difference in frost damage appears to occur because of dif- ference in elevation. This grower, who for- merly used gasoline engines on his wind machines, reports that he has better suc- cess and more dependability with his present Diesel engines. From 1937 to 1947, he experienced little or no frost damage affecting yields or quality, but the last three winters resulted in: minor frost damage in 1947-48; a quality drop to 50 per cent orchard run and 50 per cent excellent quality (Sunkist) in 1948- 49 when the temperature dropped to 16° ; and, loss of all fruit but no tree damage in 1949-50. He credits the wind machines with saving his trees during the 1949-50 freeze, when the temperature one night dropped to 15° for three hours. 3. The East Highlands Orange Com- pany has 1,200 acres of citrus in the East Highlands area, 40 per cent being Va- lencia oranges and 60 per cent navel or- anges. Forty acres are equipped with a total of four dual 100 h.p. wind machines and Jumbo Cone heaters as supplements for frost protection. In the 1948-49 winter, nearly all of the fruit was lost on the 1,200 acres of fruit, even with the wind machines and 45 heaters per acre going on the entire grove. However, there was no tree dam- age, even though the temperature fell to 17° one night and to 20° in some parts of the grove. There was almost as much damage from snow that winter as from frost, since the snow softened the fruit and caused it to rot. To experiment with the wind machines one night that winter, the manager turned the machine off on one of the two areas protected by wind machines at a time when both areas were being held at 26° with the machines go- ing. Within fifteen minutes, the tempera- ture dropped to 23° where the machine had been turned off but remained at 26° in the part of the grove protected with the other machine. Neither tree nor fruit damage occurred to any extent during the winter of 1949- 50. The manager of this large grove com- mented that fruit can stand lower tem- peratures later in the year than otherwise, stating that a temperature of 28° inside the fruit is dangerous early in the year, with 26° being the danger point towards the latter part of the winter season. He thinks that a fruit thermometer is needed so that temperatures inside the fruit can be measured. He concluded his experiences by men- tioning that it was necessary to light heaters on 12 nights during the 1949-50 winter, except on the wind machine acre- age where only 4 nights of border heat- ing were required. According to the man- ager, the cost was only % to y± as much with use of wind machines and heaters as compared to the use of heaters alone on this grove. 4. No heaters are used in a 30-acre Valencia orange grove, located about one mile west of the main highway between Fullerton and Anaheim. However, two dual 100 h.p. wind machines have been installed here since 1948. The grower says that, down to 24°, fruit can be saved with wind machines alone. Even 21° can be safe for a short period, he thinks, adding that wind ma- chines should be kept running late in the morning to gradually thaw out oranges which might have slush ice in them. This grove has never used heaters. In 1936-37, practically all of the fruit was [21 lost, but there was no tree damage. In 1947-48, there were 6,000 field boxes of fruit lost on 9 acres. This loss occurred in a cold spot of the grove where the land dips and is intermixed with both large and small trees. Since the wind machines have been installed, losses have been as follows: 5 per cent fruit loss in 1948-49; a few young trees killed in 1949-50. Two gasoline engines have had to be replaced in two winters on the wind ma- chines. The machines rotated in 15 min- utes the first winter of their installation but in 12 minutes the next. They do a better job with the slower rotation, ac- cording to this grower. 5. A grower with a 17-acre lemon grove, located in the Claremont area, ex- perimented during the 1949-50 winter by putting a 12% h.p. electric wind ma- chine on the south quarter of his grove. His idea was to try to suck air from in back of his machine, which oscillates 180° on the south 4^ acres, in an at- tempt to protect the entire grove (17 acres) . On the coldest nights, he used scat- tered firing on the south portion of his grove, heavy firing on the north and east border (drift side) and burned one heater to every other tree in the grove except the south portion. His results showed that a cold pocket was created directly behind the machine and that his fruit losses were heaviest there. The south quarter of the grove averaged a yield of 900 field boxes per acre while the rest of the grove had an average pick of 700 boxes per acre. Temperature differences, between the part of the grove under wind machine protection and elsewhere, were not notice- able on the night of December 11-12, 1949. This grower concludes that the movement of air in itself must be bene- ficial. He now has installed 3 additional 12% h.p. electric oscillating machines on his 17 acres. This grower also commented that on a cold night a grower can save 50 per cent of the oil cost by using a wind ma- chine with heaters as compared to using heaters alone. On moderately cold nights, he thinks that the wind machine-heater combination will save 75 per cent of the oil and all of the cost for this fuel item on a low ceiling, frost night. Finally, he says that border firing with or without a wind machine may not be needed if other growers are firing from the drift side. 6. An Arlington Heights (Riverside city area) grower reported that his or- anges went Sunkist on 15 acres, after the 1948-49 season, by using a 100 h.p. elec- tric wind machine for frost protection, supplemented by 100 heaters on only one night. His original reason for installing the machine was to keep cold air from accumulating in his grove as a result of the operation of a neighbor's dual gaso- line machine. Severe fruit loss and some tree damage resulted during the 1949-50 winter on this grove, the losses being the heaviest on the south side of the grove and on 5 acres farthest from the machine. That year, no heaters were lit and the pitch of vertical angle of the 13V2-f 00 t airplane type propeller was changed, as compared with the year before. Since the air blast from the machine was actually shaking trees 7 rows away, the pitch of the propel- ler was changed towards the horizontal position. The result of this change, ac- cording to this grower, was that the ma- chine now overshot the grove somewhat and "pinned" cold air down into the south portion of his grove on a night when the drift changed and the temperature stayed at 24° for 6 hours. He comments that he thinks two smaller machines might have been better than the large one on his 15 acres. 7. The Riverside area grower men- tioned above has another grove in the Arlington Heights, and it is equipped with a 100 h.p. electric wind machine. An airplane engine was formerly used to power the machine but it was changed because the grower was afraid that an [22] airplane engine mechanic might not be available if something went wrong. Due to the shape of his 20-acre orange grove, this grower thought that a neigh- boring grove was getting the benefit of the machine on the downdrift side. There- fore, he installed a speed-up and slow- down device so that his machine would spend less time facing the neighbor's grove when it rotated. However, he dis- covered that 500 field boxes of his own had to go orchard run after the 1949-50 winter, this fruit quality loss occurring in the area where the machine rotation had been speeded up. The new device has now been taken off and the original, uni- form rotation resumed. 8. Frost experience in the Mentone and Crafton areas near the city of Redlands was reported by a grower who has 130 acres of Valencia and navel oranges. Forty acres of the 130 acres located in the Mentone area are under heaters, while one-half of the 90 acres in the Crafton area are heated. This grower suffered severe losses in the 1948-49 winter, and where he didn't heat, his fruit loss was nearly 100 per cent. Where he heated, he thinks that his fruit returns were greater than his cost of heating. It was necessary to heat 7 or 8 nights that winter, using 45 heaters per acre in the Mentone area and 30 per acre in the heated part of the Crafton grove. Practically no fruit loss or tree dam- age resulted from the 1949-50 freeze, where heating was practiced. Five nights of heating were necessary. Fruit loss ex- ceeded 25 per cent on 12 acres of his un- healed acreage in the Crafton area. Wind machines may not be efficient in the Crafton area, comments this man, since there is a moving drift in this area, whereas a wind machine is best used in a cold dead air pocket. Besides, in 15 years, he figures that he has averaged only 2 nights of heating per year. Oil pipeline heaters are used on 30 acres in the Crafton area by this grower. He says that they are the best heaters on heavy soil because the difficulties involved in filling after a rain are avoided. 9. A grower with 20 acres of navel or- anges in the Arlington Heights area, near the city of Riverside, says that he had about 15 per cent fruit loss each season during the winters of 1947-48, 1948-49, and 1949-50, in addition to some tender growth tree damage. In 1949-50, young replants were killed on his grove. One dual wind machine is now used in conjunction with heaters on this acre- age, one heater per tree being located in the first 3 to 6 rows on the borders. When necessary, every other heater in the two outside border rows are lit to begin with, the border on the drift side being fired first. Every other heater in these rows is used as a reserve in case the first heaters fired run out of oil. Return gas stack heat- ers, which will burn all night without re- quiring refilling, would eliminate the need for each alternate heater, comments this grower. 1 0. Twelve acres of 4-year old Valencia trees are part of a 25-acre grove which also includes a few plums and the balance in avocados. This grove is equipped with a dual 100 h.p. gasoline wind machine and heaters as a supplement. The temperature in the grove got down to 23° during the 1948-49 winter, but the oranges and avocados didn't freeze with the wind machine going and heaters burning in the drift corner (northeast) on the west border and in a particularly cold spot below the center of the grove on the east border. Something about the movement of air in itself seemed to help here since other groves near by, which experienced these same temperatures that winter, froze. The operator of this grove thinks that the compression of air by a wind machine may produce heat which is utilized by the trees and fruit. He also comments that as the air gets colder, it also gets heavier and, therefore, the ma- chine's propeller moves less of it. [23] COVERAGE ... is a major factor in deciding how to make best use of your frost protection investment. Here are some facts on coverage by heaters alone, wind machines alone, and heaters with wind machines. COVERAGE: HEATERS ONLY Data collected from 50 groves equipped solely with heaters show no fixed mini- mum in the number of heaters thought to be necessary for adequate coverage. The highest number reported per acre was 100; the lowest 10. The total array in terms of heaters per acre of grove was found to be as follows: 10, 16, 18 (two cases), 21, 25, 26, 27 (two cases), 28 (two cases), 30, 32, 35 (two cases), 36, 38, 39, 40 (six cases), 41, 42, 43, 45 (five cases), 46, 49, 50 (three cases), 60 (four cases), 62, 63, 64, 65, 66, 67, 83, 89, 100. Growers frequently point out that fir- ing of all the pots is not generally neces- sary. They plan to light a portion of the pots when the temperature reaches a cer- tain level, and then to light additional pots if and when the temperature con- tinues to drop. Thus a grower may light every fourth pot at the start, follow (as temperatures drop) with another fourth, continuing until he is satisfied that suf- ficient heat is being provided to insure the safety of his fruit, or of his trees if he decides to sacrifice the fruit in the interest of economy. As a rule, orange growers who practice frost protection without wind machines usually have from 25 to 50 bowl or dis- tilling types of heaters per acre in their groves, with about 50 per acre being the most common number. Lemon growers, depending solely upon these types of heaters for frost protection, seldom install less than 50 or 60 heaters per acre. The number of distilling type heaters required varies with the grove location, the specific kind of heater or heaters, age of trees, type of fruit, number of trees per acre, etc. One very important variable that de- termines the need for more or less heaters is the amount of heating which takes place in a district. So-called "mass heat- ing" of citrus area- ma\ mean that low temperatures within those areas are gen- erally raised even in groves which prac- tice no heating. The frost protection aid to a given grove from other groves is usually greatest when air warmed b) the heaters of others moves with the natural air drift into an orchard. Also important in determining the number of heaters required I as well as their placement I is the kind or kinds of distilling type heaters used. The hot-stack or combustion-chamber type heaters, such as the Jumbo Cone, Return-Stack, and 7-inch Exchange, have more of their heat output available as radiant heat than lazy flame heaters. This fact may have some influence on the number of heaters required, especially on nights when con- vected heat has a tendency to rise without warming the trees. Those heaters which put out the most radiant heat are espe- cially needed along the borders of the grove, since radiant heat is the kind which reaches the trees and fruit in straight lines without dependence upon air move- ment. Lazy flame heaters, on the other hand, are more dependent upon raising the temperature of the air in order to provide heat for the orchard and there- fore are generally less effective in this respect on high ceiling nights ( also called "small inversion nights" — nights when warm air will rise rapidly because an area or layer of warm air does not exist a short distance above the grove). As border heaters, lazy flames are often ineffective in protecting trees and fruit facing the drift, especially a cold one, since it is difficult to immediately raise the tempera- [24 ture of a large mass of air when it first moves into the orchard. There is generally no advantage in hav- ing fewer but larger heaters (combustion type) . A very large number of small (lazy flame) heating units distributed in the grove is generally more efficient, because of the more uniform distribution of radi- ant and convective energy. When oil pipeline or generating heat- ers are used, it is common to install about 25 heaters or less per acre, setting one heater in the center space of 4 trees. The general plan is to burn the heaters at a high rate, about 1 gallon per hour, and to protect 4 trees with the heat from each burner. However, tests made in southern California during 5 winters (1937-42) by the Division of Agricultural Engineer- ing, University of California, showed that on nights of high ceiling these heaters were even less effective in raising grove temperatures for a given amount of fuel than the lazy flame type. The usual patterns, when the distilling or bowl heaters are used, are to have either one heater to every tree in every other row, or one heater to every other tree in every row. The first pattern offers the advantage of simplicity and conven- ience in firing and filling, while the second generally results in a more uniform dis- tribution of heat, especially radiant heat. If heaters are placed in the tree spaces instead of in the tree rows, radiant heat distribution is more uniform although radiant heat loss to the sky is greater. It should be pointed out that even though a grower has one heater for two trees in- side his grove, using either of the two patterns, he may often need to fire only half or fewer of these heaters on some nights to gain adequate frost protection. Border heating. Extra heaters must often be placed on border rows, especially if a grove does not receive benefits from neighboring heating. A common practice used by growers with groves isolated in such a way that the natural air drift does not carry previously warmed air into their groves is to keep one heater out- side of each border row tree facing the incoming drift. According to recent tests by the Agricultural Engineering Division, University of California, border heaters should be distributed over the first 2 or 3 rows from the edge of the grove rather than being concentrated solely on the out- side of the orchard, and in isolated or- chards, where border heat is usually needed on all sides, with the greatest num- ber on the upwind drift side. Under usual conditions with reason- ably flat terrain and low wind velocity, recommended border spacings for iso- lated orchards are as follows : 4 times as many heaters per tree outside of the or- chard on the upwind or drift border as are used within the orchard; 2 times as many for the first 2 rows in from the edge as are used within the orchard; never more than 2 heaters per tree on the outside nor less than 1 heater per 2 trees on the outside and the first row in along the upwind or drift border; on borders, except on the drift side, 2 times as many heaters per tree on the outside (and possibly on the first row in) as are used within the orchard, and never less than 1 heater per 2 trees on the outside. One very interesting fact, discovered in the University of California tests, is that the rising stack gasses and heated air over an orchard create an updraft which draws in cold air from all sides of the grove even on the downwind side directly against the prevailing airdrift. This ex- plains why border heaters are needed on all sides of an isolated orchard. COVERAGE: WIND MACHINES ONLY The following summary of manufac- turers' and growers' estimates does not include all of the wind machines on the market. It is confined to those on which enough information was gathered during this study. 12V2 h.p. electric. Coverage for this machine seems to be about 5 acres or [25 more. To be conservative one should probably not attempt to cover more than 5 acres with this machine, and in addi- tion use heaters when necessary. How- ever, others risk putting this small-size machine on 7, 8, or even 10 acres. The manufacturers themselves say that it will cover 6 to 10 acres. They also think that heat is necessary as a supplement to their machines on the colder nights. 25 h.p. electric. Five to 7.5 acres ap- pears to be, a reasonable coverage, provid- ing, of course, that heaters are sometimes fired with the machine, especially on the high-ceiling nights. Some growers put a machine of this kind on 10 acres, with the thought of firing extra heaters on the area which might fall outside of the wind machine influence part of the time. 50 h.p. electric. Coverage for this machine is about 10 acres. 60 h.p. electric. A figure of 10 acres' coverage appears about correct. 1 00 h.p. electric. Growers' estimated coverage is 11 to 20 acres. This figure corresponds to the manufacturer's recom- mendations. 100 h.p. gasoline. This machine is usually adequate for 10 acres when sup- plemented with heaters. It may not give any coverage at temperatures below 20° F even with many heaters burning. In the coldest areas, it would be wise to have from 40 to 60 heaters per acre for a pos- sible supplement, especially on lemons. In warmer locations, 5 to 20 heaters per acre may be sufficient insurance against failure of the wind machine to do the job alone. Experience in certain areas, such as in some parts of Orange County, may give the grower sufficient confidence in the weather so that he will not need any heaters at all. Dual 100 h.p. gasoline. Coverage with this machine is usually from 10 to 20 acres, averaging about 15 acres. Twenty acres may be effectively covered even without heaters, down to about 24° F, and certainly during mild winters. Some growers purposely put machines of this kind on 20 acres, realizing that perhaps 5 acres or more of that acr< will need to be fired heavily on cold nights when they fall outside of the range of the machine. This method is used with other machines. Coverage may be onl\ 10 acres on moderately cold nights with no heaters fired. On very cold nights, cov- erage may be only 10 acres even with heaters. Experience has shown that if the weather gets cold enough, nothing will give protection against both fruit and trees except perhaps over a limited area. Within usual expectations, however, the conservative grower in a cold area will attempt to cover 10 acres with this ma- chine while others may find it more eco- nomcial to take slight risks of frost damage with a machine to every 1 5 to 20 acres. Dual 110 h.p. gasoline. The evi- dence gathered would indicate that this machine will cover about the same as the dual 100 h.p. One point worth mention- ing about this machine is that the 110 h.p. industrial 6-cylinder engine, designed for stationary use involving constant loads, apparently stands up longer under wind machine use than the 100 h.p. V-8 engine. 145 h.p. gasoline. 10 to 12 acres seems the range of this machine. 210 h.p. diesel. This machine will protect 15 acres or more under normal conditions if heaters are used as a sup- plement on the colder nights. Without heaters, it is difficult to make any definite predictions. Acreages from 10 to 15 could probably be protected without heaters depending upon weather conditions. It would be definitely unwise to try to pro- tect any acreage at all in locations which have a reputation for being consistently cold without supplementary heaters. This is true for any wind machine. COVERAGE: HEATERS WITH WIND MACHINES A majority of growers supplement their wind machines with heaters to be used [26] when the temperature cannot be con- trolled or sufficiently modified entirely by a wind machine. Exceptions in the joint use of machines and heaters are those groves so located that they benefit from the heating of their neighbors by the prevailing drifts. Also, some groves are located in areas where temperatures seldom fall below 25 degrees, such as in certain parts of Orange County. The joint use of machines and heaters means a smaller number of heaters, per- haps only % to % the number required when a wind machine is not a part of the equipment. Conditions governing the placing of heaters vary from grove to grove, partly because of the influence of topography, nearness of hilly areas, low spots of poor air drainage, natural air drift direction and velocity, heating programs of neigh- boring groves, presence of windbreaks, open fields, etc. Border heating. The above condi- tions necessitate care in placing the heat- ers. Placement is predicated upon the coverage of the wind machine (varying from 5 to 20 acres). The most common pattern is to use one distilling heater per tree (between the border trees and the path of the air draft) on the updrift border or borders of a grove. This in- volves heaters on one or two borders, or approximately 65 for a square 10-acre orchard. Many growers, especially during the freezes of 1948-49 and 1949-50, have had to light more than one heater per tree on the drift border or borders. Also, it was necessary in many cases to fire more than the border rows, such as row 1, row 3, row 5, etc., counting rows in from the outside border row (row 1). This was especially true on extremely cold, high ceiling nights, where acreages per machine were relatively large or where protective coverage by a machine was ineffective on outer grove areas due to their shape. Some heater patterns used are such that 3 or even 4 borders are supplied with heaters for firing in case of changing drifts or the decreased radius of coverage of a wind machine on a high ceiling night. The need for outside border heaters is usually the greatest on the updrift border or borders of a grove. This is because the wind machine is generally able to cover more radius with the drift than against it (occasional changes of drift are usually of only short duration ) and also due to the fact that the air should be warmed, if possible, by heaters on the drift side of the orchard before it strikes the out- side border trees and is circulated by the machine. This is especially true when a high ceiling night exists, since the air is uniformly cold at the ground and above the trees, neighboring heat having a tend- ency to rise without being carried with the air drift into other orchards. Also, on these high ceiling nights, the need for heaters on 2, 3, or 4 borders is increased. Some growers purposely install machines on acreage that are too large to be cov- ered on the coldest nights. They claim that it is more economical to light more heaters in those areas which sometimes fall outside of the range of influence of the machine than to cover less acreage per machine. Machine rotation. In orchards where oscillating machines are used, the prob- lem of decreased coverage against the drift is not applicable except, of course, in case the drift reverses. Heaters are al- ways fired on the updrift border or bor- ders when 180-degree oscillating machines are placed at from 40 to 100 feet inside an updrift border. This is also true on the coldest nights in the case of a machine os- cillating 90 degrees from the drift corner. The advantages in using radiant or combustion type heaters on grove borders in preference to those having lazy-flame type stacks are probably the same whether a wind machine is used or not. Interior heating. In addition to bor- der and border area heating, growers sometimes have found it necessary to [27] light heaters scattered within the interior areas of their groves, but not too close to their wind machines. One pattern of fir- ing, inside the grove, that has proved to be generally successful in conjunction with border firing on the coldest nights is where about one heater to every fourth tree in every fourth row is lit. This pat- tern will prove helpful on the coldest nights although it should not be needed within 75 to 100 feet of the machine. One caution that every grower should note is that heaters should not be fired in a con- centrated line perpendicular to the blasts of air from the wind machine if any pro- tection is expected beyond that line of Table 12. Cost of Buying Heaters as Reported by Growers. Some Costs Are Approximate. Acreage Type of heater Number of heaters Year purchased Cost per heater Cost per acre 10 10 10 10 20 10 5 10 20 10 5 5 10 17 5 12 10 10 10 6.5 10 7 20 10 10 5 12 15 15 15 20 Butane pipeline Citrus regular Citrus regular Citrus regular Exchange 6-inch and 7-inch diameter Hy-Lol929 Hy-Lo Giant Jumbo Cone Kittle (drip type) 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 18-inch lazy flame 24-inch lazy flame 24-inch lazy flame 24-inch lazy flame 24-inch lazy flame 24-inch lazy flame 24-inch lazy flame 24-inch lazy flame 24-inch lazy flame 24-inch lazy flame University return stack University return stack (with- out bowls and covers) Oil pipeline (incl. distributing system) Oil pipeline (incl. distributing system; 370 450 400 700 900 500 239 600 1,200 527 250 240 500 510 265 744 300 300 400 585 660 265 500 420 340 300 495 750 750 750 130 430 1933 1922 1920 1920 1937 1929 1929 1941 1930 1938 1938 1938 1942 1924 1936 1944 1935 1937 1920 1945 1937 1945 1940 1946 1948 1947 1944 1945 1938 $4.70 2.50 2.75 2.75 3.00 2.40 3.25 2.95 5.00 1.76 1.60 1.60 2.50 1.50 1.65 2.75 2.00 2.00 3.75 2.77 2.50 2.97 2.50 2.60 3.00 2.25 3.20 3.50 5.60 2.80 7.35 8.29 $ 173.90 121.50 110.00 192.50 135.00 120.00 155.40 177.00 300.00 92.75 80.00 76.80 125.00 45.00 87.45 170.50 60.00 60.00 150.00 249.30 165.00 112.44 62.50 109.20 102.00 135.00 132.00 175.00 280.00 140.00 191.10 178.23 [28 fire. The reason for this is that a concen- trated row of heaters fired will set up a "wall of fire," through which it will be difficult or impossible for the wind ma- chine blast to penetrate. Frozen fruit and trees resulted from this practice during the 1948-49 and 1949-50 winters on cer- tain areas of groves which depended upon wind machines. An exception to the gen- eral rule against firing heaters in con- centrated lines perpendicular to the machine is a recommendation that from 50 to 100 heaters be fired in a circle at about 125 feet from their wind machine when needed if the drift is slight or lack- ing entirely. In case of heavy drift, how- ever, this suggests that heaters, when needed, be fired on the border or borders from which the drift comes. Spoke firing, an acceptable method of scattered firing within the grove in con- junction with border heating, is where heaters are fired starting at or near the borders and every so often part way to the machine on a line towards it (parallel to machine air blasts). One grower re- ported firing a few heaters on lines from the four corners of the grove toward the machine used. Special consideration in regard to fir- ing heaters in conjunction with wind ma- chines is sometimes given to cold spots within the orchard. Low spots of poor air drainage inside the grove may need to be fired with heaters, even though no other heat or only border firing is generally practiced. Heat should not be concen- trated, as previously mentioned, in an area beyond which the wind machine is expected to protect. If temperatures can- not be held to a satisfactory level, even with scattered firing in a low spot or other cold areas, it seems that the only alterna- tive would be to concentrate the firing of heaters both in the cold area and in the area beyond it, since the machine would no longer be effective past the wall of fire. This situation is probably a rarity and, although interesting, the average grove would not present such a problem. In the final analysis, the pattern of firing will be up to the grower. As an example of the number of heaters used in conjunction with a wind machine, and considering a square 10- acre citrus orchard equipped with a wind machine adequate for 10 acres, a liberal number of heaters might be calculated as follows: One heater per tree on four bor- ders, approximately 130; one heater every fourth tree in every fourth row in the re- mainder of the grove (90 trees per acre) , approximately 50; total number of heat- ers on 10 acres, 180; heaters per acre, 18. COSTS of frost protection are threefold: (a) initial cost of installing frost protection equipment, (b) overhead charges for use of capital so invested, (c) operating expenses. This section presents a detailed report of all three cost items for both heaters and wind machines. INSTALLATION COSTS To equip a grove for frost protection runs into a substantial sum. The following tables include examples of the capital re- quired to equip citrus orchards in various ways. Note that investments for fuel stor- age, fuel hauling, distributing equipment, and minor items are not included here. Heaters. The amount of capital in- volved in equipping a grove with heaters is determined by the kind of heater and the number installed per acre. Tables 12 and 13 show respectively the cost of equip- ping groves with heaters as reported by growers, and the 1950 prices of heaters as reported by manufacturers. 29] Wind machines. Data on the cost of installing wind machines were collected from 40 operators. These growers have installed a total of 52 wind machines. Thirty-two have one machine each; four have two each (total of eight machines) ; one has three machines, one has four, and one has five. Years of installing run : 1950, 1 machine; 1949, 25 machines; 1948, 15 machines; 1947, 3 machines; 1946, 2 ma- chines; 1945, 5 machines; 1944, 1 ma- chine. Sizes, models, and costs are pre- sented in table 14. Heaters and wind machines. Table 15 presents specimen per-acre costs of equipping groves with heaters and wind machines in combination. OVERHEAD COSTS: HEATERS Overhead charges consist of interest on the average capital invested (we are using a rate of 5 per cent for illustrative pur- Table 13. Cost of Heaters as Reported by Manufacturers (1950). Type of heater Cost per heater Date of price Remarks Hy-Lo Large Cone $5.05 plus 3% sales tax Oct. 10, 1950 Hy-Lo 24-inch lazy flame (230-A stack) $3.40 plus 3% sales tax Oct. 10, 1950 University Return Gas stack $5.60 plus 3% sales tax Oct. 10, 1950 Hy-Lo Pipeline $3.50 plus 3% sales tax Oct. 10, 1950 Company estimates that it costs $250-$300 per acre for heaters, pipe, and pumping equipment (installed) California 24-inch lazy flame $3.50 plus 3% sales tax $3.25 plus 3% sales tax Oct. 11, 1950 Dec. 30, 1950 Smokeless Lemora $5.60 plus 3% sales tax Oct. 11, 1950 Fugit-Sunray Pipeline $3.75 plus 3% sales tax Oct. 11, 1950 Company estimates that it costs $280 per acre (25 heaters per acre) for heaters, pipe, and pumping equipment (installed) Riverside Jumbo Cone Riverside Junior Louvre (18-inch lazy flame) $5.00 plus 3% sales tax Dec. 30, 1950 $2.95* plus 3% sales tax $3.25 plus 3% sales tax Aug. 1950 Dec. 30, 1950 * With square bowl. [30 Table 14. Cost of Buying Wind Machines as Reported by Growers. Size (h.p.) Model Number Costs (range) Average 12K 25 50 60 100 100 110 145 100 110 210 Electric single 10 3 5 1 1 10 1 2 1 3 1 $1,383-$1,545 $1,432 Electric single 1,854- 1,856 1,850 3,000- 3,500 3,380 3,600 3.600 Electric single Electric single Electric single 5,200 2,340- 2,970 2,700 3,600- 3,700 3,470- 4,000 3,450- 3,811 3,000 5,200 2,554 2,700 3,650 3,632 3,637 3,000 Gasoline single Gasoline single Gasoline single Gasoline dual Gasoline dual Diesel single poses — without any attempt to indicate that this should be the rate, since that is a matter of individual decision) ; depre- ciation; taxes on equipment; repairs and maintenance; and insurance (if actually carried). Interest. Number of records 32 Total number of heaters 15,315 Initial purchase price $47,075.47 Interest on average investment at 5 per cent $1,176.88 Interest charge per heater per year $.077 Average number of heaters per acre 44 Annual interest charge per acre $3.39 Interest charge on commonly used heaters (5 per cent of the average value of heaters during their life) : 24-inch lazy flame $.0875 per heater annually Jumbo Cone . . . .$.125 per heater annually University return stack $.140 per heater annually Depreciation. — A charge for depre- ciation covers wear and tear (and in some cases obsolescence) . It is determined from the first cost, less any salvage value when discarded, divided by the years of service- [ able life. In our collection of data we did not attempt to differentiate between dif- ferent makes of heaters. Growers' evi- dence was at best somewhat incomplete and largely a matter of opinion rather than of measurement. Yet it is appropri- ate that a charge to cover return of capital invested in heaters is proper business and accounting procedure. Our basis for calculating the average depreciation shown below was as follows : life of heaters in lemon groves, 15 years; life of heaters in orange groves, 20 years. Number of records 32 Number of heaters 15,315 Purchase price of heaters $47,075.47 Average purchase price per heater 3.07 Depreciation per heater per year: Lemon groves 20.5 cents Orange groces 15.3 cents The following shows the depreciation charge on an acre basis: Number of records 32 Total number of heaters 15,315 Number of acres served 344.5 Average number of heaters per acre 44 Annual average depreciation per heater (lemons and oranges) . $.18 Annual deprecation per acre per year $7.92 31] .as o o o o o o O O O 2 9 o o o .■s * q oq o q oq co ^ M O oq co ^ o co H 00 H cn os cc H H CO to CO in d i> •2 P. 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I CO • V eel ,d cc CO V cd cc CO CD 4 CQ '*+ •— S to d d*a CD CD bo tx •^ -3 •= o 2c > o 5 Tt lH Q T- bo esi D hii'O t §5 a a e t d d a a c 4 d c a x o u: , d d e a a ^ IO o c B.00 N N 1C > io io c rji f t- iH T- 0) o tH tH Cn CN CN i- iH T- iH CN CS »H O. > cS 3 Jfi'o O 4) ■81 io m it > O O C > o o c o c o o c 4) a) •Si * 1- iH r-i i- 1 H rl r iH i- iH rH t- Depreciation of specific heaters based on use: 24-inch lazy flame — Cost new $3.50; depreciation of bowl and cover, $.14 an- nually (20 years life) ; depreciation of stack (cost $.70) — annual charge per stack as follows: 0-20 hours burning, $.06 (12 years life) ; 21-40 hours burn- ing, $.07 (10 years life); 41-60 hours burning, $.09 (8 years life) ; 61-80 hours burning, $.12 (6 years life). Total cost: 0-20 hours, 20 cents; 21-40 hours, 21 cents; 41-60 hours, 23 cents; 61-80 hours, 26 cents. Jumbo cone — Cost new $5.00; depre- ciation of bowl and cover, $.14 annually (cost $2.80, 20 years life) ; depreciation of stack (cost $2.20) — annual charge per stack as follows: 0-20 hours burning, $.31 (7 years life) ; 21-40 hours burning, $.37 (6 years life) ; 41-60 hours burning, $.44 (5 years life) ; 61-80 hours burning, $.55 (4 years life). Total cost: 0-20 hours, 45 cents; 21-40 hours, 51 cents; 41-60 hours, 58 cents; 61-80 hours, 69 cents. University return stack — Cost new $5.60; depreciation of bow and cover, $.14 annually (cost $2.80, 20 years life) ; depreciation of stack (cost $2.80) — an- nual charge per stack as follows: 0-20 hours burning, $25 (11 years life) ; 21-40 hours burning, $.31 (9 years life) ; 41-60 hours burning, $.40 (7 years life) ; 61-80 hours burning, $.56 (5 years life) . Total cost: 0-20 hours, 39 cents; 21-40 hours, 45 cents; 41-60 hours, 54 cents; 61-80 hours, 70 cents. Repairs and maintenance. Calcu- lations based on (a) replacing one stack during the life of heaters so equipped at an average annual cost of 4 cents per heater, and (b) other outlays for repairs amounting to 4 cents per heater per year, result in a annual average outlay of 8 cents per heater. With an average of 44 heaters per acre, the average annual re- pairs and maintenance amounts to $3.52 per acre. Outlay for return gas stack heaters may be about 17 cents per year per heater. Summary of Average Overhead Charges on Heaters. Per heater Per acre cents dollars Depreciation 18 7.92 Interest on investment. ... 7.7 3.39 Repairs and maintenance. 8 3.52 Taxes inconsequential Insurance inconsequential Totals 33.7 15.43 Overhead charges on miscellaneous equipment used with heaters: Thermometers (one for each 2 acres) — cost new $3 each; depreciation $.30 annually for each thermometer (10 years life) ^interest, $.075 annually. Thermometer shelters (one for each 2 acres) — cost new $5 each; depreciation, $.50 annually for each shelter (10 years life) ; interest, $.125 annually. Lighting torches (one for each 2% acres) — cost new $4 each; depreciation, $.27 annually for each torch (15 years life) ; interest, $.10 annually. Flashlights (one for each 10 acres) — cost new $1.75 each; depreciation, $.17 annually for each flashlight (10 years life) ; interest, $.044 annually. OPERATION COSTS: HEATERS Survey data were collected covering 31 groves in 1947-48, 47 groves in 1948-49, and 48 groves in 1949-50, showing the cost of operating heaters. Data for all three years were not always available, as heating practices varied with different groves and from year to year. The first year was a considerable frost year; the second and third were heavy frost years. These data deal with abnormal firing activities. Heater operation cost data tabulated next page [33 Number of acres equipped for heating: 453,75 acres. Number of hours of heating: 1949-50 3,218.5 hours 1948-49 3,975.5 hours 1947-48 1,226.0 hours Average cost of fuel, labor, and total per acre : Fuel Labor Total 1949-50 $60.29 78.39 20.99 $25.14 33.67 17.54 $ 85.43 1948-49 112.06 1947-48 38.53 Average number of hours of heating per acre : 1949-50 1948-49 1947-48 7.1 8.8 2.7 Average cost of fuel, labor, and total per-acre hour Fuel Labor Total 1950-49 $8.49 8.90 7.77 $3.54 3.82 6.50 $12.03 12.72 14.27 1949-48 1947-48 Marked differences in outlays for fuel and labor, hours of use, cost per acre, number of hours per acre, and cost per acre-hour occur. There is a close correlation between outlays for fuel and labor and hours of use. In other items the data vary markedly. Extent of the variations in cost per acre for fuel and labor are tabulated below. 1949-50 1948-49 1947-48 Cost per acre : Highest $300.00 $286.90 $84.00 Lowest 24.35 36.00 4.49 Number of records reporting costs per acre of : Less than $50 5 1 21 $50 to $100 22 14 10 101 to 150 11 19 151 to 200 6 9 201 to 250 3 3 251 to 300 1 l o Total 48 47 31 An especially interesting variation is that shown in cost of heating per hour. The data show : * * Two of the 1949-1950 records reported no outlay for heating in 1948-1949 and seven in 1947-1948. [34] 1949-50 1948-49 1947-48 Highest cost reported $42.00 $55.00 $26.00 Lowest cost reported 5.71 4.50 1.67 Number of records reporting costs per hour of : Less than $4.00 1 $ 4 to $ 8 12 7 10 8 to 12 12 17 12 12 to 16 8 9 9 16 to 20 5 3 20 and over 5 4 3 Total records 42 40 35 Detailed cost items of heater Cleaning heaters — Jumbo cone operations. Detailed examples of opera- (combustion chamber type) — $.008 per tion and overhead costs of heating appear heater hour (prorated each year on a in tables 16, 17, and 18. They are based basis of one cleaning after each twelve upon the best estimates available from hours of burning). Twenty-four inch growers and others. Operation cost esti- lazy flame (simple cylindrical stack, mates are as follows: without automatic regulator) — $.006 per Moving heaters — (in and out from un- heater hour (prorated each year on a der trees) $.05 per heater annually basis of one cleaning after each twelve (labor and equipment costs included), hours of burning). University return Filling heaters — $.09 per heater an- stack — $.001 per heater hour (prorated nually (labor and equipment costs in- each year on a basis of one cleaning after eluded). each 100 hours of burning).* Both hoses and buckets are used in fill- Emptying heaters — $.09 per heater ing. Those who do custom work almost annually (labor and equipment cost in- always use buckets exclusively instead of eluded. hoses because of their greater adaptabil- Disposing of sludge — $.001 per ity to varying conditions such as tree heater hour (prorated on a basis of one spacings, ground condition, etc. In a real disposal after every fifty hours of burn- rush after a night of firing, buckets are ing, labor and equipment costs included, probably faster for filling than hoses. One operation not necessary for University re- disadvantage of buckets is that they must turn stack heaters) . be carried once or even twice to the heater. Painting heaters — $.024 per heater If the heater is almost empty, it takes two annually (no charge made for use of trips to fill each one (9-gallon bowl and paint brush or waste oil). 5-gallon bucket) . Firing heaters — $1.00 per hour of fir- Gear pumps are often used where hoses ing for each man (1 man for 5 acres) . serve to fill heaters. This speeds up the Stand-by labor thermometer process of filling with hoses. reading and supervision — 25 per cent When possible, growers drive their of the cost of labor for actual firing, tanks (mounted on a truck or pulled with Charge for oil — $.08 per gallon, a tractor if the tank is mounted on a Consumption of fuel oi/t — Lazy trailer) down the row without heaters flame: .5 gallons per heater hour. Jumbo (called the dark row) and fill heaters in cone: .7 gallons per heater hour. Return the two rows on either side with buckets stack: .7 gallons per heater hour. or hoses or sometimes both. 7T 7 . . n ->„. , A _ _ „ ""In actual practice these heaters have hurried Refilling heaters— $.02 per gallon we ll over 100 hours without requiring cleaning. (labor and equipment costs included) . f Variable. [35] Charge for torch fuel (kerosene- gasoline mixture) — $.25 per gallon (use one gallon per 175 heater hours) . Cost of oil storage — $.01 per gallon used. This is based upon the rate charged growers for storage and handling by the Orchard Protection Company of Upland, California. FUEL STORAGE COSTS Fuel storage is accomplished in one of three ways. Growers may have storage facilities on their groves, belong to a co- operative storage association, or they may combine these two methods. On-the-grove storage consists of bolted or welded steel or galvanized iron tanks, placed aboveground or under- ground, or tanks made of concrete, rein- forced with steel, and placed under- ground. Oil to be used in pipe line systems should not be stored in galvanized tanks. A chemical reaction between the oil and zinc produces zinc soaps and makes trouble in pumps and small valves. Table 16. Estimated Cost of Heating 10 Acres of Citrus Using 50 24-Inch Lazy Flame Heaters Per Acre. (An Average of 35 Heaters Per Acre Is Assumed to Be Fired at Any One Time During Hours of Firing.) Annual costs Operating costs : Moving heaters Filling heaters Refilling heaters Cleaning heaters Emptying heaters Sludge disposal Painting heaters Firing heaters Stand-by thermometer reading and supervision Oil Torch fuel Operating costs Overhead Costs Depreciation of heaters Interest on heaters Depreciation of miscellaneous equipment Interest on miscellaneous equip- ment Overhead costs Total cost Cost per acre 10 $ 25.00 45.00 none 14.00 31.50 1.75 8.40 2.00 5.00 140.00 5.00 $ 277.65 $ 100.00 43.75 5.25 1.44 150.44 $ 428.09 42.81 [36] Annual hours of heating 20 $ 25.00 45.00 63.00 28.00 31.50 3.50 8.40 4.00 10.00 280.00 10.00 $ 508.40 $ 100.00 43.75 5.25 1.44 150.44 $ 658.84 65.88 40 25.00 45.00 126.00 56.00 31.50 7.00 8.40 8.00 20.00 560.00 20.00 $ 906.90 $ 105.00 43.75 5.25 1.44 155.44 $ 1,062.34 106.23 80 $ 25.00 45.00 252.00 112.00 31.50 14.00 8.40 16.00 40.00 1,120.00 40.00 $ 1,703.90 $ 130.00 43.75 5.25 1.44 180.44 $ 1,884.34 188.43 Table 17. Estimated Cost of Heating 10 Acres of Citrus Using 50 Jumbo Cone Heaters Per Acre. (An Average of 35 Heaters Per Acre Is Assumed to Be Fired at Any One Time During Hours of Firing.) Annual costs Annual hours of heating 10 20 40 80 Operating costs Same as preceding table (except oil) $ 137.65 196.00 $228.40 392.00 $ 346.90 784.00 $ 583.90 1,568.00 Oil Operating costs Overhead costs Depreciation of heaters $ 333.65 $ 225.00 62.50 5.25 1.44 $620.40 $ 225.00 62.50 5.25 1.44 $ 294.19 $ 1,130.90 $ 255.00 62.50 5.25 1.44 $ 2,151.90 $ 345.00 62.50 5.25 1.44 Interest on heaters Depreciation of miscellaneous equipment Interest on miscellaneous equip- ment $ 294.19 $ 627.84 62.78 $ 324.19 $ 384.19 $ 914.59 91.46 $ 1,455.09 145.51 $ 2,536.09 253.61 Cost per acre The minimum amount of storage re- quired for the distilling bowl type of heater is probably about 1,000 gallons per acre or 30 to 50 gallons per heater. The minimum capacity required for the oil pipe line heater system is 1,500 to 2,000 gallons per acre. More storage capacity is required for pipe line heaters than bowl or distilling types because of the required higher grade of fuel, more difficult to obtain on short notice. Cooperative storage is the most popular in the Redlands, Upland, and Pomona districts. An estimated 90 per cent of the growers who heat in the Red- lands-Highland area belong to coopera- tive storage associations, but 10 per cent have additional storage on their groves. Three of the 12 associations in that area have supplied the information which fol- lows. The Crafton-Mentone Protective Association is the only organization of 12 not associated with a packing house. The Barton Protective Association of Redlands has 455,000 gallons of storage tank capacity. It is incorporated as a non- profit organization, has 69 grower mem- bers at present (November 13, 1950). and sells shares of stock representing 1,000 gallons of storage each. The market value of the stock varies from $25 to $30 per share. Assessments of $3 per share are made each year to cover overhead and in addition there is a handling charge vary- ing according to the volume of oil used each year. The charge for 1949 was $.50 per thousand gallons used, which is a relatively low rate due to the large amount of oil withdrawn for orchard heating. The Santex Protective Association of Redlands has a capacity of 1,250,000 gal- [37] Table 18. Estimated Cost of Heating 10 Acres of Citrus Using 50 Univer- sity Return Stack Heaters Per Acre. (An Average of 35 Heaters Per Acre Is Assumed to Be Fired at Any One Time During Hours of Firing.) Annual costs Operating costs Same as preceding table except cost of removing sludge negligible Overhead costs Depreciation of heaters Interest on heaters Depreciation of miscellaneous equipment Interest on miscellaneous equip- ment Overhead costs Total cost Cost per acre 10 $331.80 195.00 70.00 5.25 1.44 $ 271.69 $603.49 60.35 Annual hours of heating 20 $616.90 195.00 70.00 $888.59 88.86 40 $1,103.90 225.00 70.00 5.25 1.44 $ 301.69 $1,405.59 140.56 $2,137.90 350.00 70.00 5.25 1.44 $ 426.69 $2,564.69 256.46 Ions. The association is incorporated as a nonprofit organization, has 152 mem- bers (November 13, 1950), and sells shares of stock which entitle members to 1,000 gallons of oil storage per share. The market value of the stock is $30 per share. Assessment and handling charges are pro- rated among the members. The Crafton-Mentone Protective As- sociation of Redlands has a capacity of 1,750,000 gallons. Tanks are made mostly of corrugated galvanized iron, although the new tanks are made of electrically welded steel. One hundred thirty growers belong to this organization which is incorporated as nonprofit. One thous- and gallon shares or storage have a mar- ket value of $20 to $25 each, with a par value of $20. The assessment for fixed overhead (taxes, rentals, management, insurance, etc.) is $1 per year per share. A charge for depreciation is an additional $1 per share and a service charge is made which varies from $.40 to $1.50 per thousand gallons of oil used each year. In the Upland area, about 80 per cent of the citrus acreage which is heated gets its oil through the Orchard Protection Company, according to the secretary of that organization. Four packing houses, Upland Lemon Growers, Upland Heights, Upland Citrus, and the Old Baldy Citrus Association, own the stock in this non- profit corporation. Growers belonging to those four packing houses use the oil which is stored by the Orchard Protection Comany. The growers pay 1 cent over the original cost of the oil to cover the costs to the company. Other packing houses in the Upland area, beyond those which own the stock in the Orchard Protection Company, have their own storage and sell oil to their grower members. One of the advantages of storing oil is that it costs less to buy from the refinery [38] in the summer than in the winter. A repre- sentative of the Crafton-Mentone Protec- tive Association states that it costs one- half cent more per gallon to buy oil in winter than otherwise. Storage also as- sures avaliability of oil in the quantity and quality desired when the time comes to use it. Average depreciation of storage tanks is approximately 4 per cent for steel tanks, 5 per cent for those constructed of galvanized iron, and indefinitely for con- crete tanks. Taxes on storage tanks are about $2.00 each. Costs are given in table 19. Hauling and Distributing Oil. Oil hauling tanks are used by growers for hauling oil from a central storage center (such as those maintained by cooperative protective associations or a packing house) directly to their groves for filling heaters or for storing in their own storage tanks. In either case, the tank is eventually used to distribute oil to the heaters in the grove and, hence, it has two purposes: to bring the oil to the grove and distribute it to the heaters. Generally tanks up to 800 gallons ca- pacity are temporarily mounted on trucks of about 1% ton capacity, which provide mobile power for moving the oil to where it is needed. Customary costs consist of a charge for use of trucks (for example, $1.00 to $1.50 per hour), and for labor (for example, 2 men at $1.00 to $1.25 per hour). Some growers hire others to do their hauling and filling ; use of spray rigs consisting of truck, driver, and two work- ers (at, for example, $7.50 per hour) is not uncommon. Life of Hauling Tanks. Most growers interviewed in our study estimated a life of 20 years for hauling tanks. Taxes on farm hauling tanks are $2.00 each. Costs are given in tables 20 and 21. OVERHEAD COSTS: WIND MACHINES Overhead charges on wind machines consist of depreciation, interest on invest- ment, repairs and maintenance, taxes and insurance. Too little time has elapsed to permit anything more than estimates. Growers have not had sufficient experi- ence with wind machines. Very little is known as to the probable life of these machines. Since the machines are still mostly new and in good condition, any charge reported for repairs and mainte- nance is liable to be low. Repairs and Table 19. Cost of Storage Tanks as Reported by Manufacturers. Description Price (including 3 per cent sales tax) Date of price 5,000 gallon welded steel underground (black finish) 10,000 gallon welded steel underground (black finish) 20,000 gallon welded steel underground (black finish) 10,000 gallon reinforced concrete underground 15,000 gallon reinforced concrete underground 22,000 gallon reinforced concrete underground 3,000 gallon galvanized iron 5,000 gallon galvanized iron 10,000 gallon galvanized iron [39 $454-$575 $785.89-$l,000 $1,650 $860 $1,080 $1,250 $375 $530 $1,046 Sept. 1, 1950-Apr. 1951 Sept. 1, 1950-Apr. 1951 Apr. 1951 Oct. 11, 1950 Oct. 11, 1950 Oct. 11, 1950 Apr. 1951 Apr. 1951 Apr. 1951 Table 20. Recent Costs of Hauling Tanks as Reported by Growers. Size of tank, gallons Year purchased Cost 270 280 300 360 450 1948 1949 1949 1944 1946 $ 75.00 60.00 75.00 100.00 147.00 Table 21. Cost of Hauling Tanks as Reported by a Manufacturer. Capacity Gauge steel Price of tank only Price mounted on skids Add for fittings 3 per cent sales tax Total prices complete 500 14 $ 96.05 $117.30 $43.07 $4.81 $165.18 550 14 99.53 120.78 57.48 5.35 183.61 695 14 112.79 138.29 57.48 5.87 201.12 830 14 127.75 155.80 72.48 6.85 235.13 1,000 12 164.43 192.48 72.48 7.95 272.91 maintenance normally increase with the aging of a machine or implement and there is no reason to doubt that this same situation will hold with wind machines. This is particularly true of motors. Occa- sional replacement of engines or motors is necessary. Grove operators' estimates of the life of the wind machines — the basis for fig- uring depreciation — are summarized be- low: Gasoline engines, 8 to 20 years, with an average of 15 years (one reported the ex- pected life of his engine at 1,000 hours, while another gave his estimate as 600- 800 hours or 5 years) . Electric motors, 10 to 20 years, but mostly 10 years. Towers, 10 years to an indefinite life, but when specific figures were given the average was close to 28 years. Wooden propellers, 7 to 10 years, with 10 years the most common figure. Operators accepted 5 per cent on in- vestment as a fair charge for capital in- vested in wind machines. Data concerning repairs and mainte- nance are admittedly sketchy. The actual figure, as reported by grove operators was $1,448.96 per year on motive power — an average of $96.00 per grove. In addition, painting towers and cleaning propellers added another $13.00 per grove. Repairs and maintenance consist of engine tune- up, new batteries, fan belts, spark plugs, replacing fuel pumps from time to time, painting towers (usually once in four years), propeller care, etc. Taxes to date have not as yet been standardized. One county (San Bernar- dino) assesses at 50 per cent of market value. With an initial cost of about $3,000, the assessed value is taken only on $1,500. At this rate, the tax the first year is $90.00. The assessment is to be gradu- ated down with each additional year of aging. Thirty-five hundred dollar wind machines are reported as assessed in Orange County at $750*.00. With a pre- vailing tax rate of $4.00 per $100.00, the tax is $30.00. As a general figure, a tax of ».00 per machine appears average. [40] Insurance is not usually carried, al- though there were some cases where in- surance was in force. One operator reported a premium of $3.00 annually for lightning hazard insurance; another reported insurance against fire and light- ning, explosion, cyclone, tornado, wind- storm, riot, strike, and civil commotion, aircraft and vehicle, theft, vandalism, and maliciousness (premium of $19.00 an- nually for each of 4 wind machines) ; two reported insurance premiums of $8.00; two more of $16.00; and one of $13.00 per machine. One insurance agency, in Upland, reported that they have insured more than 20 wind ma- chines, all but one of them being gasoline powered. Their rates for insurance cover- age listed for the grower above paying $19.00 annually per machine are $1.87 for 3 years per $100.00 of value (gasoline machines), and $1.50 for 3 years per $100.00 of value (electric machines). Even though the carrying of insurance on wind machines is not uncommon, the evidence makes it appear that today in- surance is not to be considered much of a factor in estimating the overhead charges. Annual overhead charges for va- rious types of wind machines, as set forth in table 22, are based on the follow- ing estimates from growers, manufac- turers, and other competent sources : ?2'/2 h.p., 25 h.p., and 50 h.p., electric. Depreciation based upon initial cost and 15 years life of entire unit; in- terest, 5 per cent of average value of machine during its life; repairs and maintenance, $5.00 charge made to cover painting, greasing, and other minor items. Single 100 h.p., gasoline. Depreci- ation based upon a replacement charge of $300.00 for an engine with a life of 7y 2 years, and the initial cost of the bal- ance of the unit with a life of 15 years; interest, 5 per cent of average value of machine during its life; repairs and main- tenance, $35.00 for motor tune ups, spark plug care and replacement, battery re- placement, fuel pump repair and replace- ment, etc.; $7.67 prorated annually to take care of one minor overhaul of engine during its life, and $9.00 for tower and propeller painting and care. 175 h.p., gasoline. Depreciation based upon a replacement charge of $450.00 for an engine with a life of 10 years, $75.00 for a wooden propeller with a life of 3 years, and the initial cost of the balance of the unit with a life of 15 years ; interest, 5 per cent of average value of machine during its life; repairs and maintenance, $35.00 for motor tune-ups, spark plug care and replacement, fuel pump repair and replacement, etc.; $19.60 prorated annually to take care of one minor overhaul of engine during its Table 22. Annual Overhead Charges for Various Types of Wind Machines. Make and type of wind machine Initial cost Annual depreciation Average Annual annual interest repairs and maintenance Total annual overhead 12 ^ H.P. electric $1,590 1,890 3,785 2,606 2,106 3,605 3,270 $106.00 126.00 252.33 193.71 175.40 280.33 268.00 $39.75 47.25 94.63 65.15 52.65 90.13 81.75 $ 5.00 5.00 5.00 50.67 63.60 88.33 25.00 $150.75 25 H.P. electric (440 volts) 50 H.P. electric Single, 100 H.P. gasoline 175 H.P. gasoline National dual, 100 H.P. gasoline 210 H.P. Diesel 178.25 351.96 309.53 291.65 453.79 374.75 [41 Table 23. Operating Costs of Wind Machines as Reported by Growers. Type : 12 K h.p. electric motor Number of machines Hours operated (total) Cost of power : Standby charge $ 607 - 38 Energy 546 ' 43 10 2,222 $1,153.81 Total *1' 153 - 81 Cost of labor Inconsequent Cost of incidentals Inconsequential Cost of power, labor and incidentals Cost per hour of operation Number of acres served 79 Average acreage served per machine 7 - 9 _ 14. bU Cost per acre Type : 25 h.p. electric motor Number of machines 1 Hours operated (total) 263 Cost of power : Standby charge $ 120.00 Energy 64 - 98 Total $ 184.98 184.98 Cost of labor Inconsequential Cost of incidentals Inconsequential Cost of power, labor and incidentals 184.98 Cost per hour of operation - 70 Number of acres served 1° Average acreage served per machine 10 Cost per acre 1850 Type : 50 h.p. electric motor Number of machines 5 Hours operated (total) 1.549 Cost of power : Standby charge $1,258.14 Energy 803.19 Total $2,061.33 2,061.33 Costof labor 100-00 Cost of incidentals Inconsequential Cost of power, labor and incidentals 2,161.33 Cost per hour of operation 1-40 Number of acres served 50 Average acreage served per machine 10 Cost per acre 43.23 Type : 60 h.p. electric motor Number of machines 1 Hours operated (total) 225 Cost of power : Standby charge $255.85 Energy 142.13 Total $397.88 397.88 Continued on next page. [42] Table 23. Operating Costs of Wind Machines as Reported by Growers. (Continued) Cost of labor Inconsequential Cost of incidentals Inconsequential Cost of power, labor and incidentals $ 397.88 Cost per hour of operation 1.77 Number of acres served 10 Average acreage served per machine 10 Cost per acre 39.79 Type : 100 h.p. gasoline engine Number of machines 8 Hours operated (total) 2,445 Costof fuel 3,743.90 Costof labor 301.00 Cost of incidentals 112.75 Cost of fuel, labor and incidentals 4,157.65 Cost per hour of operation 1.70 Number of acres served 75.5 Average acreage served per machine 9.4 Cost per acre 55.07 Type : dual 100 h.p. gasoline engine Number of machines 7 Hours operated (total) 1,937 Costof fuel , 4,561.51 Cost of labor 815.00 Cost of incidentals 136.59 Cost of fuel, labor and incidentals 5,513.10 Cost per hour of operation 2.85 Number of acres served 90 Average acreage served per machine 12.9 Cost per acre 61.26 Type : dual 110 h.p. gasoline engine Number of machines 5 Hours operated (total) 1,005 Cost of fuel $2,437.94 Cost of labor 467.67 Cost of incidentals 63.75 Cost of fuel, labor and incidentals 2,969.36 Cost per hour of operation 2.95 Number of acres served 67 Average acreage served per machine 13.4 Cost per acre 44.32 Type : single 210 h.p. diesel Number of machines 1 Hours operated (total) 140 Cost of fuel 89.00 Cost of labor 15.00 Cost of incidentals 1.00 Cost of fuel, labor and incidentals 105.00 Cost per hour of operation .75 Number of acres served 15 Average acreage served per machine 15 Cost per acre 7.00 [43] life, and $9.00 for tower and propeller painting and care. Dual 100 h.p., gasoline. Deprecia- tion based upon a replacement charge of $600.00 for two engines with a life of 7% years each, and initial cost of the bal- ance of the unit with a life of 15 years; interest, 5 per cent of average value of machine during its life; repair and main- tenance, $60.00 for motor tune-ups, spark plug care and replacement, fuel pump repair and replacement, etc.; $13.33 pro- rated annually to take care of one minor overhaul of engines during their life, and $10.00 for tower and propeller care. 2 10 h.p,, diesel. Depreciation based upon a replacement charge of $750 for an engine with a life of 7% years, and the initial cost of the balance of the unit with a life of 15 years; interest, 5 per cent of average value of machine during its life; repair and maintenance. OPERATING COSTS: WIND MACHINES According to information supplied by growers, the cost of operating wind ma- chines is made up of ( 1 ) cost of fuel or electricity; (2) cost of oil and other inci- dentals; and (3) operating labor. These items are shown in table 23, the table setting forth (a) number of hours operated; (b) total cost of fuel or elec- tricity (including standby charges in the case of electric motors) ; (c) total cost of incidentals; (d) total cost of labor; (e) total all operating costs; (f) cost per hour of operation; and (g) cost per acre. DISCUSSION ... of frost protection measures now centers on the questions of what wind machine to buy, and whether supplementary heating should be used. This section analyzes these questions and concludes by summarizing the comparative costs of frost protection methods. CHOOSING A WIND MACHINE Many growers have been faced with the problem of what kind of wind ma- chine to buy, if any. This is indeed a problem in the light of the various factors involved. Minimum required horsepower per acre. One important argument being waged between companies is that of the small machine vs. the large machine. The basis of disagreement is whether or not a certain amount of horsepower is neces- sary per acre. As shown in the remarks on manufacturers' estimates of wind ma- chine coverage (page 25), three of six wind machine companies say that at least six horsepower output at the propeller per acre is necessary for frost protection. The remaining companies made estimates of from 1% to 4% horsepower per acre for adequate coverage. All of the companies are partly right, depending upon varying factors. Twenty acres of citrus is generally accepted as being the maximum amount of coverage that any one machine can handle. Many times, this is only true under certain weather conditions. Some growers may claim 20 acres of coverage but expect to use heaters extensively on the outer edges of the grove, at least on the coldest nights. In reality, their machines are not actually covering 20 acres at all times. Undoubt- edly, at least 6 horsepower at the propel- ler per acre is necessary for coverage as high as 20 acres. Smaller acreages may require less horsepower per acre than larger acreages. This is due to the fact that the farther [44] air is forced away from the propeller, the lower is the efficiency achieved as to the distance that air can be moved, per horsepower. Probably any machine of less than 50 propeller or brake horse- power should be considered as a small machine. However, it must not be over- looked that the distance air is moved is not directly proportional to the acreage covered or the adequacy of coverage. Nonetheless, up to a maximum of about 10 acres coverage, less than six horse- power per acre may give satisfactory re- sults. It is possible that about 2 to 5 propeller horsepower per acre will be suf- ficient to cover areas of 5 to 10 acres. A big problem is whether or not some of the smaller, less expensive machines can take care of as much as 10 acres. Certainly, the question as to how many horsepower per acre are necessary is not easily answered, nor is it the only con- sideration when choosing a wind ma- chine. Dr. F. A. Brooks of the Agricultural Engineering Division, University of Cali- fornia at Davis, says that from 5 to 8 propeller horsepower per acre are neces- sary for frost protection, according to tests he has conducted. Rotator movement. Another factor involved in choosing a wind machine is rotator movement. The two most com- mon methods of rotator movement are the 360 degree rotation and oscillation. Oscillation is where the wind machine platform, upon which the motive power and propeller are mounted, moves alter- nately clockwise and counterclockwise without completing a 360 degree rotation. Variable speed devices, speed-up and slow-down mechanisms used on rotators, have not been used extensively, although they may yet be of considerable utility. Experiments by Dr. Brooks, using these devices, may provide answers as to how they could be used to advantage. The 360- degree rotation of a constant speed is at present the most common kind of a rota- tor movement, especially on square or nearly square groves. Different degrees of oscillation, mainly the 180 and 90 de- gree sweep, have more recently come into favor. The biggest objection to the 360-degree rotation is the fact that it is harder to blow against the natural air drift than with it. Air drift, although usually not more than three miles per hour in velocity, is still a very important factor in the coverage of a wind machine. Ma- chines which make a full rotation are usually offset from the center of the grove towards the upwind or drift side. For instance, if the drift is from the north- east, a wind machine is generally offset to the north and east of the center of the grove. In a square 10 acres, with a north- east drift history, machines are usually offset 20 to 100 feet to the north and east of center. Many growers, even though they have had their machines offset in this manner, still complain of difficulty in attempting to blow against or "buck" the natural air drift. A typical example of how coverage is affected by the natural air drift was re- lated by a representative of one wind ma- chine company. In tests, their machine is said to have pushed air 260 feet against a 2.9 mile per hour drift, 370 feet cross drift, and 500 feet with the drift. The answer to offsetting drift is to be found partly in the use of oscillating ma- chines, blowing more or less with the drift almost all of the time. They promise espe- cially effective results in areas which have a fast drift — a 3-mile per hour drift being considered fast. Three of the six major wind machine companies sell oscillating machines. One company sells exclusively a type of machine which oscillates 90 degrees from the drift corner. It is powered with an airplane engine which generates 47 propeller horsepower. It is claimed that this machine will reach 820 feet directly with the drift and that the coverage is 10 acres. However, the manufacturer adds that it is necessary to light heaters more often and sooner in the areas which 45 are farthest away from the machine. He says that there is little correlation between horsepower and frost protection. He cites as an example that if you increase your oscillation to 130 degrees, instead of 90, you can push air only a maximum of 350 to 400 feet. This is purportedly due to the fact that increasing the span of oscil- lation decreases the advantage of the pro- gressive pushing of air. Another company sells both oscillating and rotating types of machines, but re- cently reported that about 60 per cent of their sales were for oscillators. These machines can be set for any degree of oscillation, although most of those sold move 180 degrees. This company believes in placing oscillating machines about 40 feet in from the grove border on the drift side. This is so that heat can be carried into the machine when it is necessary to light heaters in back of it on the upwind or drift border. A company engineer esti- mates that the radius covered by a wind machine will be about 25 per cent more with the drift than otherwise. However, it should be remembered that the acreage covered may be less than with a rotating machine because the area of protection is not the full 360 degrees. A factor to consider is that occasionally there is a change in drift. The danger of frost damage in the case of a machine oscillating from the drift corner might be great if the drift were to reverse com- pletely. For example, if the natural air drift were to change from northeast to southwest and the machine were oscillat- ing from the northeast corner of the grove, coverage would be greatly reduced. This same difficulty would apply if a ma- chine were oscillating 180 degrees near the north border and a usual north drift reversed to south. It is noteworthy at this point to mention a small wind ma- chine company, not discussed elsewhere, which sells a machine designed to take care of 10 acres and to oscillate 180-190 degrees. This machine, using a 110 h.p. Ford 6 industrial engine and selling for about $2,700, is placed 100 feet In from the center of the border on the drift Bide. Heaters are supposed to be fired in the area to windward of the machine if it gets too cold. A less serious change, in the case where a machine is placed to oscillate directly with the drift, is that where the drift changes but does not completely reverse. A complete reversal of drift is also less dangerous when the machine is not oper- ating directly with the usual drift. Thus, if a machine is placed near the center of the west border and the usual drift is from the northwest, a complete reversal of drift will make the machine operate crossdrift almost the same as before. Changing drifts also affect the cover- ages of rotating machines, but the changes are not as significant as for oscillators. It is difficult to state the seriousness of the changing drifts. Usually these drift changes last only about 15 minutes in most of the citrus areas. Growers are probably the best judges of the direction and variability of their drifts. Past ex- perience in an area will undoubtedly give an operator knowledge as to what to ex- pect in this respect and he may draw his own conclusions as to the danger in- volved. It has been said that oscillation makes for better coverage on the acreage reached than rotation. This is entirely within rea- son since a given tree within the range of the machine is opposite the propeller blast or jet more often with an oscillating than with a rotating machine. Propellers vary in speed, rotation, size, and shape. It is to be expected that they will also differ in efficiency. One company, making electrically driven machines, states that propellers should be designed for a particular set of conditions. The airplane propeller which is used on some wind machines was originally designed for traveling con- ditions and not static wind machine use. Hence, one company is designing its own propellers. [46] One wind machine company uses a four-bladed propeller instead of the usual two-bladed one. Another unique feature of their propeller is that it is of the tractor type, meaning that it pulls air into and back over the machine. The advantage of this type of propeller, according to the manufacturer, is that it gives the greatest amount of unrestricted blade area on the vacuum side. It is also claimed to prevent the overshooting of near-by trees. This propeller revolves at about 800 r.p.m. Probably the most interesting type of propeller is three-bladed and is made of 16-gauge sheet metal, in contrast to the usual wood or aluminum propellers. The most unusual feature of this propeller is that it revolves horizontally instead of vertically and at only 155 to 175 r.p.m. It uses from 21 to 26 brake horsepower, which originates from a gasoline engine or electric motor at ground level, and is transferred directly to the propeller by a vertical drive shaft. The advantage claimed for this propeller is that it creates a "vortex," meaning that air is recircu- lated after it travels to a point of equilib- rium. Thawing. Reports were collected of fruit having been thawed out using wind machines during the winters of 1948-49 and 1949-50. Machines kept running un- til as late as noon following nights of apparently damaging temperatures are claimed to have gradually unthawed frozen fruit, resulting in no damge. Con- sidering for the moment that this practice could assure growers of frost protection without heaters down to minimum tem- peratures of about 20 degrees, undercir- culation rather than overcirculation would seem dangerous. Larger horse- powered machines would probably be better for this thawing out process, al- though it has not been determined that the smaller machines could not accom- plish similar results if they were kept run- ning until late in the morning. The pos- sibilities involved in this subject, as well as in the more general idea of whether or not the movement of air in itself is beneficial for frost protection, may cer- tainly have a bearing upon the choosing of a wind machine. Costs. Overhead and operating costs undoubtedly enter into the question of what kind of wind machine to buy. Not only costs of owning and operating the wind machine, but the additional costs involved in supplementing the machine with heaters, enter into the choice. Past records concerning weather (pages 16- 18) will provide a rough guide as to how many hours of frost protection are needed and whether or not heaters will be re- quired to supplement the wind machine. WIND MACHINES— WITH OR WITHOUT HEATERS? Based on growers' experience to date, the conclusion emerges that a combination of wind machines and heaters offers the maximum frost protection for the citrus in- dustry. Wind machines alone cannot always reach enough warmer air to mix with the cold to maintain temperatures sufficiently above the critical point. This is especially true if the air is clear and the ceiling high. Heaters alone under some condi- tions will fail to reach all parts of a grove. Further, when the air is clear and the ceiling high the heated air has a tendency to go straight up beyond the useful zone. While no final statement can be made at this time as to whether or not heaters are absolutely necessary with wind ma- chines on citrus, it is probable that heat- ers are necessary in most localities in which citrus is protected from frost. How- ever, during the winters of 1948-49 and 1949-50, results using wind machines alone were fair to good in some parts of Orange County. Other counties have areas in which results were good with no firing of heaters in conjunction with wind machines, even on the cold nights. When outside of the grove temperatures L 47 drop below 25 degrees on oranges, the wind machine is not fully capable of con- trolling frost. The grove then requires additional heat. Although there has been some evidence that the movement of cir- culating air is beneficial in itself, nothing certain has been proved. The danger involved in using wind ma- chines without heaters is illustrated by the tests of citrus coverage made by Mr. William Rogers of the United States Weather Bureau at Pomona. On low ceil- ing nights, the coverage for a dual 100 h.p. gasoline machine, without heaters, was 20 acres, but only 7% acres of pro- tection were obtained on very cold, mod- erate ceiling nights. If heaters are used with wind machines, they are not usually fired except on the coldest nights. Even though it proves un- necessary to light them even once during the year, the grower does have them as a kind of insurance. The necessity for insurance of this type will depend mainly upon the location of the grove and the consequent frost hazard as well as the kind of fruit grown. Lemons require use of heaters more often than oranges be- cause of their greater susceptibility to frost. On the whole, citrus growers should have heaters in their groves to supplement their wind machines on cold, high ceil- ing nights. Where experience has shown that heaters are not necessary (the win- ters of 1948-49 and 1949-50 were excel- lent tests of whether or not there is need for heaters) in conjunction with a wind machine in certain fairly frost-free areas or localities, growers may be saved money by not buying heaters. Heaters already already available in the grove should cer- tainly be retained for possible use, pro- vided that no better use can be made of them. It should be remembered that high or moderate ceiling nights make the wind machine, by itself, less beneficial in keep- ing temperatures above those which are critical for citrus. Many growers have expressed the opinion that on certain nights, their wind machines were making their groves colder. Whether this is true or not, it is apparently a fact that on some so-called "freeze nights" with a high ceiling, the wind machine has little or no warm air overhead to circulate and hence it may be dependent upon some supplementary source of heat t<> main- tain or raise temperatures. The equaliz- ing of temperatures within the grove itself by the circulation of air may prevent frost damage for a short time, but the only safe answer to the cold high ceiling nights is to fire some heaters. Finally, one reason that has possibl) been overlooked by growers as to the necessity for using heaters with wind ma- chines is that the benefits from mass heat- ing will decrease if more growers install machines. The time when each grower will have to depend almost exclusively upon his own frost protection devices and not those of his neighbors could be brought about if all growers bought wind machines. Even though wind machines are supplemented with a limited number of heaters, the grove-heating efficiency of the machine-heater combination prob- ably means that little heat would be wasted. COMPARATIVE COSTS OF FROST PROTECTION METHODS Table 24, a composite of several previ- ous tables, is designed to show compari- sons of the annual cost of different and typical methods of protecting citrus from frosts. Where heaters and wind machines are shown as being in joint use, it is assumed that the wind machines are operated twice as many hours as the heaters. 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d o 03 ea I > Pi O a 2 • O 41 bo ^2 a (9 43 43 c 43 4: c J) g 2 1 *5 4J § CO 1 tH « 4 o tH « CN O -fi ^H c8 cq ■" Eh A 1- e3 p o tN 1 P O CN a •0 V CO o © 'co e8 pq « ► P co o »- lO IO * n E o a*3 tH iH Estimates of 50 heaters per acre with- out a wind machine and 18 heaters per acre with a wind machine were used (see discussion on the number and placement of heaters, page 24). An average of 70 per cent of the heaters burning during the actual hours of firing has been as- sumed in our estimated costs. (This is undoubtedly high for some districts but does reflect growers' estimates.) Acreage assigned to each wind machine is dis- cussed on pages 25-26. Conclusions. Table 24 shows that the cost per acre-hour for different methods of frost protection varies considerably. Not only are different methods respon- sible for variations in per acre-hour costs, but the number of hours of operation influence to a large extent the costs in- volved. According to the data, wind machines and heaters show no marked difference in cost per acre-hour for 10 hours of annual operation. The combinations of machines and heaters at 10 hours have a wider range of costs than wind machines alone or heaters by themselves. However, both of the gasoline machines (a single 100 h.p. on 10 acres and a dual 100 h.p. on 15 acres) in combination with heaters, show less cost per acre-hour than heaters alone. In comparing per acre-hour costs of gasoline and electric wind machines, the following tendencies seem apparent from a study of the data : up to 40 hours, both the dual and the single 100 h.p. machines are less expensive to use than the electric. At about 80 hours of annual use, the two gasoline machines are still cheaper to own and operate than the 50 h.p. electric but cost about the same as the 12% h.p. elec- tric (on 5 acres) ; at about 160 hours, the 12% h.p. electric is the most economi- cal machine of all, with the single 100 h.p. gasoline next, and the dual 100 h.p. gasoline and 50 h.p. electric about the same in regard to per acre-hour costs. The electric machines become progres- sively cheaper to use in comparison to gasoline machines per acre-hour, as the number of hours of operation annually are increased. It should not be overlooked that wind machines are usually operated more hours than heaters in a corresponding season. This is because most growers start wind machines at about 30 degrees, and light heaters at about 29 degrees for lemons and 27 degrees for oranges. The average annual number of hours of critical temperatures for the seasons 1934-35 through 1949-50 (see tables 7-9) were: Claremont area — 13 hours of 27 degrees and lower, representing 28 per cent of the total of 49 hours at 30 degrees and lower; Orange area — 12 hours of 27 degrees and lower, represent- ing 28 per cent of the total of 54 hours at 30 degrees and lower; Redlands area — 18 hours at 27 degrees and lower, repre- senting 31 per cent of the total of 77 hours at 30 degrees and lower. For 1949-50, growers in our study using wind machines reported : under 100 hours of operation — 3 per cent; 100 to 200 hours— 26 per cent; 200 to 300 hours — 43 per cent; 300 to 400 hours — 20 per cent ; 400 to 500 hours — 3 per cent. In 1949-50, growers interviewed who use heaters only reported : under 90 hours of operation — 63 per cent; 90 to 120 hours — 35 per cent; more than 120 hours — 2 per cent. Although no definite conclusions can be drawn from the above, it indicates that growers may use wind machines at least twice as many hours on an average (oranges and lemons not distinguished) as they use heaters alone. If this is true, then a grower comparing costs of using a wind machine with heaters might use the total cost for 20 hours of machine operation to compare with 10 hours of heater operation for the same amount of frost protection. Analysis reveals that wind machines alone still compare favorably with heaters in the cost of owning and operating, even if it is necessary to operate them twice [53] as many hours as for heaters. Since lem- ons freeze at a higher temperature than oranges, hours of wind machine opera- tion required for lemons will be closer to the hours of heater operation necessary for frost protection than for oranges. Considering 2 hours of wind machine operation as equivalent to 1 hour with heaters, the following facts appear: The 12% h.p. electric machine is cheaper at 20 hours or more than heaters alone ; The 50 h.p. electric machine is cheaper than heaters at 40 hours or more than heaters alone; The 100 h.p. single and the 100 h.p. dual gasoline machines are both cheaper at 10 hours or more than heaters alone; The 12V2 h.p. electric machine-heater combination costs about the same per acre at 40 hours but is cheaper at more than 40 hours of operation than heaters alone; The 50 h.p. electric machine-heater combination is cheaper at 80 hours or more than heaters alone; The 100 h.p. single and the 100 h.p. dual gasoline machines, when used with heaters, cost about the same per acre at 10 hours of operation, but are cheaper at more than 10 hours of operation than heaters. These conclusions should be taken with reservation. At best, only generalities can be made about frost protection. Some of the reasons for variations which compli- cate the findings when applied to the indi- vidual grove are: (1) costs per hour vary from grove to grove and from time to time, depending upon natural and eco- nomic factors as well as practices followed by individual growers and corporations; (2) hours of critical temperatures vary from year to year and it is impossible to forecast how much and what kind of frost protection will be needed; (3) growers differ in the amount of risk that they will take, particularly in regard to the temper- atures at which they start wind machines and light heaters. MONEY AVAILABLE FOR FROST PROTECTION If frost control measures are going to be financed from receipts from a grove, then each presents a problem of determin- ing what sum is available from the sale of fruit, after deductions have been made for expenses other than frost protection, in- cluding sums for family living, payment of debts, and maintenance of the equip- ment, trees, and other capital items. Thus, if data are compiled showing the economic situation for a given grove, an idea can be obtained as to ability to pay for heating either from (a) current earnings; or (b) an increase in the quan- tity or quality of fruit sufficient to meet the expenses of frost protection after this increased expense of caring for a large crop — picking, hauling, etc. — is first covered. Sample sheets for compiling economic data for the individual grove are given in Appendix I, page 57. YOUR GROVE IS AN INDIVIDUAL PROBLEM From the mass of material brought to this report, the fact is clear that each grove presents an individual problem both as to the best type of frost protection and the justifiable investment in frost control measures. Several factors justify this view. 1 . There is no uniformity in the frost occurrence pattern. Prevalence of frost sufficient to require heaters or wind ma- chines, or both, varies markedly from year to year in both a given locality and a given grove. Operation of heaters or wind machines thus follows no definite pattern. Much use may be needed some years and little or none in other years. 2. Selection of proper equipment de- pends on the size of a grove, its shape, its topography, direction of prevailing winds, etc. 3. The use of frost control measures varies with the kind of fruit. Lighting of [54 heaters customarily takes place when the orchard thermometers drop to 28-30 de- grees in the case of lemons, and to 26-28 degrees for oranges. Likewise, wind ma- chines are usually turned on when tem- peratures drop to 30-32 degrees in lemon groves and 29-30 degrees in orange groves. However, the time of lighting heaters or starting wind machines is by no means standardized. Growers are inclined to exercise some individuality in selecting the temperature for lighting or starting. Practices one or two degrees above or below the figures cited above are not un- common. 4. The danger of frost damage also varies with the condition of the grove. Young trees, such as those that are one, two, or even three years old, are more susceptible to frost damage than older trees, and the degree of dormancy of older trees will influence the amount of damage. Semidormant trees will withstand more frost than trees that are still in succulent growing stage. FROST PROTECTION: THE LONG VIEW To concentrate solely on the freezing experiences of the last four or five years can give a distorted picture of frost dam- age. This is borne out by frost experiences extending back many years. If the cost of operating wind machines and heaters is related to the entire cycle, rather than to the 1947-48, 1948-49, and 1949-50 winters (when frost damage was much in evidence) , then the cost of frost protection naturally results in a much lower figure. More engineering studies to come. Our studies in various citrus belts of southern California bring to light a wide divergency of opinion about (1) the rela- tive advantages and disadvantages of single vs. dual engines and propellers; (2) the use of two singles at different loca- tions of the same grove vs. duals; (3) rules which should govern the locating of wind machines to conform to air currents and wind drifts ; (4) the use of oscillating platforms covering 180-190 degrees vs. complete rotations of 360 degrees; (5) possibilities of two 12% h.p. engines vs. engines with a rating of 100-110 h.p.; and (6) the acreage which different types of machines can protect. New engineering studies are being planned to meet these individual prob- lems. ACKNOWLEDGMENTS The preparation of this report involved the work and cooperation of many persons. Especial acknowledgment is due to Allister A. Allen and to Paul A. Kustel, who did practically all the field work of collecting data on growers' experiences and manu- facturers' information. Mr. Allen was employed from July 8 to September 13, 1950; Mr. Kustel from July 11, 1950, to March 28, 1951. Mr. Kustel also handled a good portion of the office work incidental to completing the manuscript of this bulletin. Others to whom credit is due include the membership of the Steering Committee responsible for this study ; to Mr. George S. B. Ferguson of Alta Loma ; to Mr. G. F. Meredith of Claremont; to Mr. Floyd Young, William Rogers, Thomas R. Crossan, Harold Rathbone, and Leland Johnson, of the United States Weather Bureau; to the Farm Advisors of Los Angeles, San Bernardino, Riverside, and Orange Counties; and, finally, to the more than 100 growers who gave freely of their time, knowledge, and experience. [55] APPENDIX I: A WORKING FORMULA FOR YOUR INVESTMENT IN FROST PROTECTION Various studies have shown us that there are citrus groves that, because of inadequate yields, high cost of operating, or other limiting factors, could not be economically equipped for frost control — either by use of heaters, wind machines, or a combination of the two. There are poor groves, the gross earnings of which are not enough to justify buying equip- ment in the first place, or, if purchased, to meet the subsequent costs of operation and maintenance, including a return of the invested capital over a period of years. Blocking off areas and labeling them as "uneconomical for frost protection," "economical," or "borderline" is not feasible. Certain areas can be designated as exposed to or fairly free from frost damage, but the lines cannot be clearly identified. One finds groves in a general frost area that are fairly frost-free; or groves in relatively frost-free areas that do suffer frost damage. Again, the earning power of groves varies markedly from grove to grove. The problem is conse- quently one of individual groves, and not areas. At an early stage of this study, some of us hoped to evolve a formula that would indicate how much firing might prove economically profitable. Our analysis leads to the conclusion that no basis can be found for determining whether or not to equip citrus groves with frost protec- tion equipment, or how much firing or blowing is economically justified. How- ever, this study does permit establishing a working formula and calls attention to the various factors that must be consid- ered in order to reach a decision on in- stalling and operating frost control de- vices. This formula is as follows: First, determine the amount of fruit saved by use of frost protection measures. Second, determine the gross value of the fruit so saved. Third, estimate the produc- tion expenses needed to pay the expenses of the added production (usually in the harvesting and hauling costs). Fourth, determine the net gain from use of frost protection measures (namely, subtract item 3 from item 2) . Fifth, determine cost of frost protection. Sixth, compare net gain because of frost protection with cost of such protection. The answer as to whether or not to provide frost protection will then emerge. It is not a simple thing to figure out but it can prove cheaper to conduct a tentative tryout rather than to buy equipment and wait to find the an- swer by trial-and-error. It is the income obtainable shown from saved fruit that will provide funds from the citrus grove to pay for investing, in- stalling, and operating heaters and/or wind machines. Is this income enough? The answer lies partly in the data pre- sented in this bulletin. Admitedly to find it calls for considerable work and the exercise of judgement. But the problem is varied and broad. Enough money can be involved to justify the expenditure of time and study in fully considering and weighing the savings, returns, costs, in- vestment, and similar items when one is confronted with the pros and cons of this important problem. A final step requires determining. This is a calculation of the cost of maintaining heaters and wind machines during years of no or very little use. The overhead and standby charges on electric motors ac- cumulate each year. This places a con- tinuing financial responsibility upon a grove. If, for example, serious frosts occur but once in five years, there will still be four years of overhead charges to be met. That these can mount to a considerable figure is indicated by the evidence set forth in various earlier sections of this report. [56] FORMULA Where heating is not practiced but where planning installation of heat protection is under consideration : Location of grove Size of grove Kinds and acreages of: Lemons Navel oranges Valencia oranges Age or ages of trees Frost losses Number of years of available records Years of frost damage to fruits (and trees) ; extent of reduction of fruits both as to quantity and quality This determination should extend back over as many years as possible. This bulletin shows serious frost years during the periods, 1912-13; 1921-22; 1936-37; 1948- 49; and 1949-50, or occurring 5 times in 38 years. If similar results were indicated for a specific grove, then the loss would be figured thus : Reduction in yield X years = Loss during frost year -f- Total number of years = Average annual loss. Example : 2,000 field boxes X 4 years = 8,000 field boxes -f- 25 = 320. Normal earning power of grove Normal Production Data (free of frost damage) Field boxes per acre Grove total Lemons Navel oranges Valencia oranges Normal Price Data n - ,, , „ , Per field box Grove total Lemons Navel oranges Valencia oranges Gross Income (yield times price — from above) r . Lemons $ Navel oranges $ Valencia oranges $ Normal Expense of Production Grove total Lemons $ Navel oranges $ Valencia oranges $ Normal Net Income (difference between receipts and expenses) r . Lemons $ Navel oranges $ Valencia oranges $ [57] Normal Allocation of Net Income Annual total For family living and other personal expenses For maintaining capital investments in grove . For discharging debts For personal income taxes (federal and state) Other Total Surplus (if any) from net income over and above allocated items Having established earnings under normal conditions the next step is to deter- mine (a) the amount of fruit saved; (b) the value of the fruit saved; (c) the cost of protection during frost years; and (d) the gain or loss. Estimate of Fruit Saved by Frost Protection (See Determination of Frost Losses Above) Field boxes Price Average annual Grove total „ ,,,, 4 rr * 1 r r Per field box 4- Total tor years for years Lemons Navel oranges Valencia oranges Grove total . $ * Due regard should be given to matter of quality as protection may increase grade, resulting in a better price. Protection Data Based on (1) a wind machine of (viz., type — 100 h.p. dual gasoline, 25 h.p. electric, etc.) ; or (2) number of heaters of make; or (3) a combination of both wind machine and heaters. Initial Costs of: Wind machine (including installation) $ Heaters (grove total) : Number Cost per heater $.... Total cost $ Combination % Determination of Use Based on an estimated average annual use: Wind machine hours Heaters: average number lighted for an average of hours [58] Average Annual Operating Costs and Overhead Charges Operating Cost : Wind machine: Electricity or gasoline charges Labor Other charges (oil, repairs, etc.) Total Heaters : Fuel Labor Other expenses (see text for suggestions) Total Total wind machine and heaters combined . Overhead : Wind machine : Depreciation Interest at % on average investment Taxes Total Heaters: Depreciation $. Interest at % on average investment Taxes Total Total wind machine and heaters combined Total Operating Costs and Overhead Charges Wind machine Heaters Combined wind machine and heaters Recapitulation Net value of production due to use of frost protection method — same for all equipment Operating costs and overhead changes Wind machine Heaters Combined wind machine and heaters Net gain (or loss) . [59] APPENDIX II: COUNTY AND CITY ORDINANCES GOVERNING USE OF HEATERS In summary form, these ordinances and the accompanying rules and regula- tions carry the following provisions: 1 . Definition of "heaters," persons, citrus orchard, frost protection, etc. 2. Permit required to erect, alter, re- place, operate or use heaters. (This per- mit obtainable from an Air Pollution Control Officer, an Agricultural Commis- sioner or a City Manager, as provided in local ordinances, county and/or city.) 3. List of approved heaters (viz., Uni- versity return stack, Pipeline, Kittle, Ex- change Model 7-inch; Hy-Lo 148 special, original, 230 and 230A 18-inch and 24- inch lazy flame; any heater with 24-inch stack, Jumbo Cone with adapter allowing for one-half inch holes, etc.) . 4. Use permitted of heaters using bri- quets, natural gas, liquid petroleum gas, electricity, wind machines, steam and hot water. 5. Use prohibited of heaters producing in excess of a prescribed minimum of solid carbonaceous matter (viz., in excess of one gram per minute) . 6. Permits to expire on November 1, following issuance. 7. Replacement schedule for noncon- forming heaters (viz., time allowed for growers to replace unacceptable heaters) . An example of this provision is the City of Santa Ana ordinance requiring replac- ing with acceptable heaters before the 1951-52 heating season a number equal to one-third of the nonconforming heat- ers, another third prior to the 1952-53 season, and all prior to the 1953-54 sea- son. Another example of replacement provisions occurring in several ordi- nances permitting use until November 1, 1951, of 65 per cent of an applicant's Class III heaters, provided the remainder of the total number shall be replaced with one or more Class I types or by convert- ing Class III types to Class I, or if any number above 65 per cent of Class III heaters are eliminated from use. Use of up to 50 per cent of Class III heaters is allowed if the eliminated half is replaced with Class II heaters, including conver- sion of Class III heaters and Class II heaters. For the year beginning Novem- ber 1, 1951, permits will be issued for use of one-half the number of Class III heaters allowed the preceding year. For the third year the use of Class III heat- ers is again reduced to one-half the num- ber allowed the previous year. No permits will be issued allowing use of Class III heaters after November 1, 1953. 8. Classifying of all orchard heaters is common to most ordinances. As a rule, four classes are set up, as follows: Class I — any type of heater that does not dis- charge unconsumed solid carbonaceous matter in excess of one-half gram per minute; Class II — the same except the limit is set at one gram per minute ; Class III — any heater which cannot be oper- ated within the limit of one gram but can be converted to a Class I or Class II heater; Class IV — any heater exceeding a discharge of one gram which cannot be converted to a type that will reduce the discharge to one gram or less. 9. Some ordinances limit the burning rate after the first five minutes following lighting. These rates vary with different types of heaters from 5 to 8 pounds of fuel consumption per heater per hour. 10. Schedule for fees for permit (viz., in Los Angeles County : less than 10 acres, $2.50; 10 to 20 acres, $5.00; over 20 acres, $7.00. Riverside County, $2.00 plus 1^ for each heater; City of Santa Ana, $1.00). 1 1 . Prohibitions against use of open fires, burning rubber tires, and certain types of heaters (viz., a total of 14, thus: garbage pail, Smith Evans, Citrus with Olsen stack, Canco 5 gallon and 3 gallon, Dunn, Hamilton Bread Pan, Hamilton Bread Pan with stack and Hamilton [60 Square Bowl, Wheeling, Chinn, Bothwell, buckets, tin cans). 12. Conditional or temporary use of certain types of heaters (viz., a total of 16, including Baby Cone, Citrus Regular, Stub Stack, Citrus 15-inch stack, Ex- change Model 5% and 6-inch diameter stacks, Hy-Lo Drumm and Hot Blast, Pheysey Beacon, etc.). 1 3. Requiring that certain makes be constructed with designated maximum primary air orifice in square inches (viz., Hy-Lo 1929. Hy-Lo 148 and Hy-Lo dou- ble stack, 0.606, equivalent to one hole of seven-eights inch diameter; Jumbo Cone 0.196 equivalent to one hole of one- half inch diameter, etc.) . 1 4. Penalties for violations and infrac- tions. 1 5. Sometimes an ordinance requires details of sale of heater oil including a statement of the flash point and other specifications, and limits fuels to kero- sene distillates, stove oils, and Diesel fuels. 15m-7,'52(9824)JB [61] AGRICULTURE . . • Contains brief, easy-to-read progress reports of agricultural research, and is published monthly by the University of California College of Agricul- ture, Agricultural Experiment Station. FIELD CROPS ORCHARDS TRUCK CROPS LIVESTOCK CALIFORNIA AGRICULTURE offers information useful to the farmer and food processor, together with announce- ments of other publications dealing with farm subjects as they are issued by the College of Agriculture. 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